Also, I've heard many people say they raised Vdimm to 2.6V - mine is currently at 2.4V. Would the combination of an increase to Vdimm and the 2.16GHz clock be too much do you think?
Go for it! Vdimm voltage only increases the voltage to the memory. This will allow for a higher FSB overclock, or more aggressive memory timings. Your Crucial memory will have no problem with 2.6V.
When overclocking remember there are two ways available with an AMD CPU. You can adjust the mutilplier, which only affects the speed of the CPU. You can also OC the Front Side Bus. OC'ing the FSB affects the CPU and memory. When OC'ing for gaming, this added memory/CPU bandwidth is more desirable. You will notice some people even lower
their mulitplier to acheive a high FSB.
Since the Barton 2500+ is such a good overclocker, I think you'll have a combination of both. First determine your max FSB speed, and then determine the max multiplier at this OC'd FSB speed. This will give you the maximum memory bandwidth, and CPU performance. I'd recommend once you've determined the maximum your system is stable at, I'd back each off a couple Mhz for increased stability.
Also, see page 4-9, 4-10 in your manual. Memory performance is a whole other topic. Basically, you want to relax (increase the numbers) to reach max. FSB speeds, or if running lower FSB speeds select Ultra, or turbo (decreases the numbers).
To get the most from your system, download SiSoft Sandra
it's a free synthetic benchmarking tool. You can use this to monitor how your FSB and memory settings are affecting memory performance.
PS. If you remove your heasink/fan, you'll need to carefully scrape off the thermal pad, and reapply thermal compound (like Artic Silver).