Don't even waste your time looking into it, just get the 7200RPM drive since the price difference is very minimal and the performance difference isn't, the 7200RPM drive is generaly much faster especialy in the area of access times.
5400 RPM drives can almost match 7200 RPM drives in STR but there is a world of difference in terms of access times. I would definately go with a 7200rpm drive like the IBM 75gxp or the Maxtor Diamondmax plus 60.
Agreed - its worth the few extra dollars for a 7200 RPM HD. Will make a noticable difference in boot time also. I also recommend the IBM 75 GXP series.
Or you really go all out and get 2 SCSI 15K RPM drives and put them in RAID 0. That would be sweet - except that you'd spend a lot more.
A more realistic suggestion - instead of geting a 60 or 75 GB drive, get like 2 20 or 30GB drives and a Promise Fasttrack card (or get a MB with a RAID controller) and use RAID 0. Then you will have almost the same speed as one of those 15K SCSI drives.