My buddy Brad built his first computer in six years. Said the hardware was easy, the software was confusing. I don’t blame him. You’d think that if you bought a 64-bit processor you’d want 64-bit Windows, well in fact, for most folks, you actually run the 32-bit Windows XP on the 64-bit processor. That gives you the most compatibility, etc. That’s true for both Athlon 64 and Intel Pentium’s with 64-bit extensions.
There are theoretic advantages to 64 bit, but the applications have to be recompiled usually and it definitely takes more memory.
Other tip is that when you do the Windows install, choose quick format. Otherwise on a 300GB hard drive, you get to wait three hours while it formats everything. Quick should really be the default. The standard format is left over from the old days when hard disks weren’t “low level” formatted. Now they all come out of the factory that way. Another legacy of the good old days.