hehe, I have the P4 530. If I had to go for a different system probably AMD would be my choice this time mostly because I like the double IDE on the boards something which misses from the Intel's 9xx chipset series.
I'll stick with my prescott 3.2ghz for now, will be a while before I upgrade... besides I have 5 or 6 processors laying around that are all at least 2.8ghz or higher, so need need for an upgrade for a while.
Same, as well, mostly when doing hard drive intense (SATA) items, do I really notice a difference. I can get on my laptop, and sometimes it seems faster, so I don't really know, it's quite hard to tell these days.