The BP6 has served me well... but about the future...
I really don’t know about the P4 Xeon. I’ve heard a mixed bag of comments (good and bad). Back in the day, there was a large difference between the P2, and the P2 Xeon, but today the difference is marginal. At this point (If I were you), I would look into dual AMD processors (please don’t hurt me for saying that). It just is the better bargain right now; unless of course you can get the Xeons for a really good price! There are lots of options to think about.