theres an anandtech faq on this but its not all correct! for a start, on bigger drives a big benefit from partitions is quicker defrag. a further point is its said that partitioning doesnt make it faster, this is rubbish if you have lots of programs and files installed, teh faq on FAT's even points out that with thousands of files on one disk "FAT32 slows to a crawl".
also he says if you reinstall windows you have to reinstall all your other programs anyway, not true as you can backup your registry!
having said that, the hassle is a pain so like the others i stick to having one partition for programs and the other for data (actually i put games on 2nd partition too as they have no problem running from there and shares out the files a bit better).