im going to suggest giving OCZ modstreams a look, got one recently, thouroughly impressed and satisfied, £58 for 520 Watt, very quiet, running two 7600GTs no problem, plus the cables supplied are good, bit rigid so they tend to be a bit hard to get out of the way sometimes, especially the thick 24-pin cable, but good, the modular system is very good and the build quality is simply fantastic, has 120mm fan which is more than upto the job, plus its very stable power, well within +/-5%
Edit: you get 3 year warranty from OCZ and the ratings are (according to the book provided) since due to your question its something you want in your PSU:
+3.3V - 28A
+5V - 52A
+12 - 28A
not sure if thats particularly good, but as i said two 7600GTs running no problem, another plus is UV reactive cables