There is no way I would buy a A1 as a primary machine. Unless you have the extra cash for a "fun" machine at their price, I certainly would go X86. Now, if you can build a A1, you can build a damn killler x86 box for well under that.
For instance, I just bought ASUS A7V8X-X for $79.99 with 3 day FedEx shipping. It supports whatever the top flavor of Athlons are out there (quick look, XP 2500 is mid range speed at $148).
As for OSs, let me point out besides everyone pissing and moaning about XP and Linux, there are other OSs you can try, like BEOS and my favorite, AROS. Considering how big and inexpensive DH's are, this gives you a bounty of OSs you can boot from.
What a cheap x86 box to run AROS from? Try
Walmart and they should have a mini-ATX at 1.1GHz for $199. Rather have a Athlon for a few dollars more? Look on
Pricewatchand see what box kit you want.
Now, if your dead set against x86, there is always a Peggy2 in Sept. =)
Dammy