PSU for new build

[Shamikebab]

Im planning on doing my first build in the summer, i'm trying to do as much research as possible beforehand. At the moment im gravitating towards the Seasonic S-12 500, however as its not modular will I have a problem fitting it into my chosen case? (Lian Li V1000+) Also will 500W be enough for my build?

Athlon 64 X2 3800
2 gig ram
X1900XTX

Also if there are any other PSU's that are better choices i'd appreciate the suggestions.

 

[Shamikebab]

do i need the extra power for my proposed spec though? or are there other reasons to go for the top model (quality, life expectancy)?

 

[Shamikebab]

Thanks for all the help guys, i think i'll go for the S-12 600.