Hard Drives

I need a new hard drive for my thinkpad r31. right now im running a 20gb 4200rpm(i think). I was looking for a 80gb, 7200rpm but read somewhere that laptop cooling sux and not to run anything over 5400rpm. now im looking at a 60gb, 5400rpm, 8mb buffer for $100. will this provide noticable improvements in speed, or do the rpms really not do much? I move alot of data, mostly downloading, copying, movin stuff around (no video editing or anything). is this a good HD for my purposes? tips for buying HDs? thanx alot

HDD 101