hmmm you should go to epox's site and check what proc's fit on your mobo. I'd take the best value for money - for example if the prices are like this

1000 mhz $100 (lowest fitting on mobo)
1300 mhz $110
1500 mhz $120
1800 mhz $200
2000 mhz $300
2500 mhz $500(heaviest for mobo)

I'd go for the $120 proc. then after lets say 2 years you wanna upgrade and just buy the (cheap by then) 2500!

an 1 gig (1000 mhz) is enough for normal browsing/mailing/word etc so go for at least 1 gigahertz. and 256 mb is a nice minimum, for a fast KDE box 512 should be better (dont believe those selling pc's who always try to give a better proc and less ram, thats bullshit. for normal work, more ram = more performance)

north/south bridge is not important
just check the max mem speed your mobo can have (something like 233/266/333) and buy that ram.

And maybe for you ARK linux whould be better, its very much targeted on newbies, very easy (4-clicks installer). Knoppix is debian, and debian isnt that easy. Nice if you want to learn, but not if you just wanna use and not wanna know...