I recently built this box for a budget minded client:
AMD Athlon XP Mobile 2400+
Shuttle AN35 Ultra
512MB Kingmax PC3200 DDR RAM
ATi Radeon 9600 128MB Video Card
Western Digital 80GB Special Edition Hard Drive
Speeze Falcon Rock Socket 462 Cooler
Lite-On 52X/32X/52X CD-RW
Antec 1650B Case w/350W PSU
The total was 474.99, 490 Shipped all from Newegg.
I know it doesn't cover everything you were looking at, but changes could be made to suit you a little better. The machine runs great, nice and cool at 2.4GHZ, and extremely quiet. I am going to be building a backup box with one of these Mobile AXP's and see how high I can overclock it with a little better cooling. I personally think if you don't mind overclocking, on a budget, one of these Mobile AXP's are going to allow you to spend more cash on things like hard drive space and memory, where you might actually see a difference in everyday apps, opposed to a few MHZ of CPU speed, which most likely would be lost except to all those who hold 3DMark and SuperPi as the only judge of a quality system. If you are going to be doing basic things, an A64 is going to be wasted on you, as an overclocked AXP will give you very similar performance in the majority of the tasks it seems you want to complete.
Anyway, just a thought, have fun and good luck on the build!