Definitely don't go low with your PSU rated wattage. If your PSU can't give you the juice that you need, you'll get odd system problems, crashes etc. I found that out 3 years ago or so. My current rig has a PC Power & Cooling Silencer 750w (before PCP&C were bought) and it's an awesome unit. When I build my next rig, it'll have a 1200-1500w power supply to power dual video, multiple drives etc.
The current issue of CPU (Computer Power User) has a large review of current power supplies, and ranks them from budget, mid-range to high-end. Well worth the read.
FWIW, I'm scoping out Corsair, Cooler Master, Antec, and OCZ brands. Look for units that are 80 Plus Certified "Gold" - these are higher efficiency, quieter, and cooler.
Good luck!