In truth, it isn't a bad idea to create a partition for games, archives and even applications if you can be bothered.
I personally would reccommend that you have at least two if you have the disk space - one for essential drivers for use in a reformat situation and the other for the core OS.
It can be difficult to work out the exact size but 20GB should be enough for the core partition and maybe 4GB for essential files.
You may also want to work out the exact size that your swap file takes up as you can place this on this own partition.. as long as its on the same disk drive then it can speed things up, as the swapfile is the most accessed windows file if it is enabled and tends to defrag alot, although to be honest with programs like O&O Defrag and its stealth quick defrag option and faster disk drives you may not want to create a partition just for this.
But my setup below is as follows
C: XP Pro OS Partition with some core windows apps (Office) and Swapfile
D: Old 24GB HD some other programs
E: CD/RW
F: DVD
G: 20GB Game Partition
H: Archive Partition with 5GB
I messed my setup up a bit, when I reformat it all I will probably try and shift more GBs into G: so its say 40GB instead of 20GB whereas the 40GB is on the C: slot. H: would be the same though.
Its all down to personal taste.. the next step of course is using your own util.. Some love Partition Magic but I personally like Paragons Hard Drive Manager as its a multi-suite toolset (it does things like copying wiping as well as standard partition stuff) and 10$ less expensive than PM but then people like different things
Useful URLS:
http://www.paragon-gmbh.com/n_fm.htm Paragon Hard Drive manager 5.5 URL
http://www.jr.com/JRProductPage.pro...Code=PQI+PM8&JRSource=google.datafeed.PQI+PM8 Partition Magic 8 URL
Edit: I original put the full Paragon Feature list up but just decided to use the basic info list as it could be overloading for some people.