first of all, you want to stay away from an Intel based machine if you want to stay under 300 bucks, theres no reason to buy an Intel P4, they are over priced as well as outdated, another thing to take into consideration is that the Intel boards are very expensive, because the good ones use Intel chipsets like the intel 845, or 865pe for 478 systems
if you want to stay under 300 i would recommend an AMD 64 with an ASUS, DFI, FIC, or ECS mobo.... although ECS and FIC are not considered a "gamers board" ive had very very good experience with both, and they are really inexpensive.
youre ASUS problem was probably 99% caused by the VIA chipset, theyre basically junk, and i recommend an nForce chipset
heres my answer to your system:
MOBO
http://www.newegg.com/Product/Produc...82E16813135175
(i have installed that board before, easy setup, it was for my grandpa)
CPU
http://www.newegg.com/Product/Produc...82E16819103572
(not the best AMD 64 but better than any other CPU for the same price or less)