Even if it proves possible to slipstream SP3 and your present CD to burn a new CD, you will of course still have all updates, both critical security updates and others issued since SP3
and all driver updates to install.
It very much depends I think on the reason for the clean install.
If for instance the clean install is the last resort to solve a problem, where Windows will simply not load and cannot be recovered by any means, other than a reinstall, then it is usually far easier to simply recover from an image.
Additionally of course, this method allows you to recover all your programs and all other files as well, but OBVIOUSLY only from when the image was made, but your personal data of course, can be restored from a simple backup.
I am not sure what this means
I bought the CD about 6 years ago and installed it on my mum's PC, stuck the sticker on the case too, then chucked it away!
as it cannot mean you chucked the CD away, unless I have misunderstood as you also say
The original sticker went walkies and it doesnt say on the cd.
I have a product key which I purchased... looking for a newer CD that'll work with it.
so, I presume you mean the case in which the CD was.
I am sure it is me not quite understanding what it is YOU NOW HAVE.
If I am correct and you have the product key AND you have the CD for that product key, then from the aspect of a clean install and making it easy by incorporating SP3, it will only REALLY be that much easier if you also slipstreamed all updates since SP3 usinghttp://www.nirsoft.net/utils/wul.html
Win Updates List and the procedure here using NLite.
Run WinUpdatesList. You'll see a list of all the updates you've installed, and sorting by date and type should show you what you've installed since the last service pack. Right-click on an update, and you'll get a link to a related Microsoft Knowledge Base article, where you should be able to download the fix directly and patch it into nLite. You can also roll executables for Windows updates—like Internet Explorer 8 which will be another update, into your disc.
see the guides section.
So in summary, apart from the small benefit of not having to install SP3, you will still have all the other updates to do, issued from SP3 and ALL this depends of course as my colleague rshaffer61
has said, on what you have and I offer for your consideration, on WHY you would view the clean install necessary.
Then of course you also have to consider
But no such luck with my Pro version. It just wouldn't accept my product key!
WHY and the answer to that will be easier I think when as my colleague has said we know what is was you bought 6 years ago and indeed what it was you bought that would not accept the product key.