I received a 60GB 120GXP as a free replacement for my dead 75GXP. I also have a dual 60GB 60 GXP RAID striping array in my system. Though the 120GXP is fast, it is no match for the RAID array. When reformatting my array I ghosted my system to the 120GXP--boot times and program loading was noticably slower. I guess I didn't think there would be much of a difference, at least not a noticable difference, but there was.
Currently I just use the 120GXP as my backup device (as well as CD's and my roomates networked machine--yes I am a bit anal about backing things up).
The 120GXP's are fast and quiet, but if you are looking for speed at a reasonable price and have a good backup plan in place, then IDE RAID is the way to go.