The top performing 7200rpm ATA drives (lower = faster)...
1) 120Gb Western Digital WD1200JB (not WD1200BB !) - $255 from Googlegear
2) 100Gb Western Digital WD1000JB (not WD1000BB !) - $200-$220 from Googlegear
3) 120Gb IBM 120GXP
4) 80Gb IBM 120GXP
5) 60Gb IBM 120GXP
The slower, quieter 7200rpm ATA drives (lower = less noisy)...
1) 40Gb Seagate Baracuda IV
2) 80Gb Seagate Baracuda IV
3) ....
4)
10) Maxtor Diamondmax D740X
My guess is that all of these drives will offer equal or lower acoustics than your older Maxtor drive, as performance/noise ratios have improved substantially in the past year. If you want a near silent hard drive, then the Baracuda IV is your only option; there is no other 7200rpm drive even close. If you want top performance, then you should go with the WD1200JB; this is essentially a version of the WD1200BB that adds 8 megabytes of cache. The WD1000JB offers 90+% of the WD1200JB's performance, and the IBM drives offers perhaps 75%.
Disk performance has a dramatic impact on system responsiveness. Whereas you may not be able to tell a difference between a 1.3GHz processor and a 2.0GHz processor in many applications, you will definitely tell the difference between a system with a top performing ATA and a system with an older, slower 7200rpm or 5400rpm drive. The speed of your hard drive directly impacts your bootup speed, the time it takes for applications and games to launch, the time it takes for web pages to load and refresh, the time it takes to copy and save files, the speed at which you can browse folders and directories on your computer, the speed at which folders and files refresh/display in Windows, etc.
Storagereview's comprehensive real world test comparison (note the WD1200JB is not included here, as it was tested later)
Storagereview is
the site for hard drive information and benchmarks. Above is a link to their recent tests; the test duplicates the performance of a drive while essentially "playing back" the disc utilization recorded for actual desktop applications (Word, Photoshop, etc) and games. You can read the full article if you want more details on the test, but I have linked the desktop benchmarks. Note the WD1200JB is a newer drive, so it was reviewed separately; it performs a bit better than the WD1000JB in the tests.