Which would be better?
 

If going from Windows to Mac on a PC?

Iatkos V7 10.5.7

or

iatkos S3 10.6.3

or something else newer???

s3 most likely, even on amd hardware snow leopard is preferable these days
If you want to go leopard, get idebeb instead of v7, its already updated to the last version and probably has better hardwaresuport