Your processor type is gonna be compatible with 99.9% of the audio programs out there. Your more likely to run into a probelm with your OS (win9x/ME/2000/XP). Athlons are so common market nowadays and they are great for running audio programs, especailly for homerecers, due to their price.
Sonar
Neundo
Cubase
Pro tools
Cool edit pro
Check em all out, see what you like.
Pro tools gives away a free version of their 5.0 version for use with 9x. Sonar has a downloadable version. I dont know about cubase, Nuendo or any of the others, but most have something that you can demo.