I recently tried to upgrade my Dell XPS 600 to 4 RAM as I use Photoshop and other photo programs, but was told by the Crucial representative that my computer will only accept 2 RAM, if it is a 32 bit XP operating system. I would like to know, if it would be too costly upgrading to 64 bit and if I would not have problems with my installed programs or maybe a workaround that might work.
I recently installed 4 GB in my XPS600 with the same result. I returned the memory. Dell support later confirmed that XPS600 motherboard reports only a maximum of 2 GB to 32 bit Windows 32 systems (XP or Vista). With many other motherboards, you can install 4 GB and get a little more than 3 GB for use by the operating system after the BIOS reserves most of 1 GB for its own address space.
Dell, however, chose to disallow *any* memory beyond 2 GB in 32 bit mode. It may have been a simple support issue whereby they didn't want the complication of dealing with memory issues when customers install 4 GB and get only 3+ GB. They may have also incorrectly forecast that 64 bit Windows would be a more popular option when, actually, it took 3+ years to be accepted due to very slow adoption of 64 bit support in drivers and software.
As to your cost question:
There is no question that it is FAR cheaper to add memory and upgrade the operating system. That should cost roughly $300 whereas a new brand name machine with 8 GB and Vista 64 would cost about $800-$1000.
The problems to deal with are:
(1) compatibility with your software, drivers, and the costs needed to upgrade them
(2) the hassle of upgrading the operating system from 32 bit to 64 bit.
Problem (1) will not be fixed with a new machine. You will still have to upgrade any 32 bit software to use the extra memory in 64 bit mode. Please note that most 32 bit programs WILL RUN in Windows 64 but only in 32 bit mode so they will NOT see or use the extra memory. I believe Adobe CS3 does load in x64 but runs in only 32 bit mode so won't use the extra memory.
Problem (2) is certainly avoided by having it installed from the factory but there is no great cost advantage other than it being bundled in the much higher cost option of getting a newer machine.
The XPS600, though quirky and aging, still has a fairly speedy processor. Mine came with a dual 3.2 GHz Pentium Extreme Edition. A newer Quad PC would certainly be faster but that's adding the cost of a new machine to your upgrade. An XPS600 with 8 GB and Vista 64 should hold its own for another 2-3 years. By then, your new machine options should be very interesting - like 6 cores, 16 GB of RAM, and Solid State Drives. Or, at worst, you'll have great deals on "old" Quad CPU's. Ha!
If your goal is to have more memory for Adobe CS3, then there are no solution. CS3 runs in 32 bit mode even if loaded in 64 bit Windows and will not see or use the extra memory. HOWEVER, Windows will see and use the extra memory for its own tasks and for running multiple programs at once even if those programs cannot use more than 2 GB.
If you DO upgrade to the newer Adobe CS4 versions which supposedly supports 64 bit in Windows only (not Mac), then upgrading to Widows 64 (XP or Vista) should give you the desired result. You should also check which of your OTHER software is Windows 64 compatible. Only the larger more memory intensive programs make use of 64 bit memory. Many well-known programs still run in 32 bit - even if running on Windows 64. Check the manufacturer web sites for each of your major software items to see if they will USE the extra memory in 64 bit, not just run in it. Beware of ad hype like "64 bit compatible" which could mean simply only that it can load and run within Windows 64 but still executes in 32 bit mode.
If you decide go to 64 bit to get more memory then you do NOT need a new machine. Your costs will be for a copy XP Pro 64 or Vista Premium 64 (Vista Premium 64 OEM versions are about $120) or Vista Ultimate 64 bit (about $190).
The XPS600 is a DDR2 machine so you want to upgrade in matched pairs of memory. It is not worth the hassle to only go to 4 GB. You should go to the max of 8 GB using 4 x 2 GB memory sticks. Prices are reasonable these days. Roughly $40 per 2 GB DDR2 chip ($160 total). Prices vary wildly on a daily basis so search the web for the best deal on a brand name with the correct specs. Also make sure you are buying single 4 x 2 GB chips all of the same model. You need that to get 8 GB in 4 slots. Many "2 GB" deals are really "2 x 1 GB" which would require 8 chips.
A note about Retail Vs. OEM Versions:
Most Internet comments suggest you can do an upgrade-in-place of Windows 32 to 64. But it is ALWAYS best to do a NAKED install to ensure you don't inherit all the problems you developed over time with the previous version. That, of course, means you would have to reinstall all your software. If possible, it is worth the hassle.
Many also report that the full RETAIL version of Vista Ultimate contains media for BOTH 32 and 64 bit Vista. I can testify, however, that the much cheaper OEM versions of Vista Ultimate DO NOT! They are either 32 or 64. Not both. OEM versions are "intended" for naked installs - not upgrades - since they are meant for newly-built naked machines. However, contrary to the fine print, the OEM versions I have bought allow for upgrades, anyway. E.g., my OEM Vista Ultimate 32 disk allowed me to upgrade my Vista Home Premium 32.
I hope the helps. In the process of writing the above, I have convinced myself to download the Windows 7 64 bit Beta to test on my XPS in a separate partition. Initial reviews suggests it is a smaller, faster, and more solid Vista. If so, then there is finally a worthy successor to XP. The hassle is it that its release is probably 9-12 months away.
PS. I cannot guarantee any of the above as 100% accurate. It is just what I have seen, read, and/or learned first hand. As always, check with your software and hardware manufacturer's for the final word. Likewise, do your own research on latest prices as they change constantly.