I am in the process of searching for new computer parts (mobo, cpu, ram and graphics card). For the CPU I have 3 choices - AMD 32 bit, AMD 64 bit, P4. I know if I go with 32 bit AMD I am limited in speed (3200+ at the most), if I go for 64 bit there may be compatibility issues. For instance, a programming language I use (dark basic pro - a 3D games language), runs fine on standard Windows XP on a 64bit CPU, but it does not run on Windows XP64 bit with a 64 bit CPU (due to emulation). If I go for P4 though, I will get faster speeds, but it will cost more and may not be as good. What do you people suggest I go for?

I don't understand your logic concerning Windows XP64. 64 bit AMD processors run fine in the 32 bit environment. Evidently you will encounter a problem with the programming language you currently use some time in the future, should you migrate to a windows 64 bit environment. This said, you will need to maintain a 32 bit OS if you want to continue using the programming language. So it has no bearing on what you do regarding hardware. If you plan on keeping the anticipated new hardware long enough to want to run WinXP64 on it, the choice is obvious. You aren't going to do that on a P4. I personnally don't look that far ahead. An example would be dual layer DVD. The drives are currently widely available but the media isn't. I don't worry about it because you learn to deal with what you have available to work with.

The CPU I'm looking at now is the 64bit 3500+. Do you think that is a good choice then?

Sounds good to me and take a socket939 system. But on thing, the internal controller of the socket939 athlon64 has a little trouble if you use 4 double sided ram sticks in dual channel mode. In that case they are automatically clocked down to 333MHz. But 4 single sided ram sticks will do well!

Would the 3500+ be comparable to a P4 3.5GHz then (if such a Pentium existed)?. ie, is it faster than the P4 3.2GHz?