Another thing that you might have forgotten, was to try de MSI K7D. At the Science Computer Departament were I work as system administrator, we're using them with dual Athlon MP 2000+ and they rock! Our server is running with 1GB of RAM (DDR) and 80GB IBM disk, Mandrake 9.0 and apache 1.3.27 configured with all the extras that Mandrake offers: php, advanced extranet,.. . It hosts web pages, an webmail and mailing lists.
We never had stability problems it runs smootlhy

I like AMD Boards, but they are not so good for servers. The K7 has no overheat protection. You mus solve this with a software solution. Its not so easy for everyone.
A overheatet AMD CPU can damage the second CPU and the board!