New PSU and GPU help

[blαh2355]

I want to upgrade my graphics card to possibly a Radeon 7790 (I prefer AMD graphics). It's a little above $100 but if anyone can recommend me something better with a price range of <$150 that would be great.

In order to upgrade it though, I also need to get a higher wattage PSU. This one, 400W: http://www.ebay.com/itm/Hercules-Silent-400W-micro-ATX-Power-Supply-w-20-24pin-SATA-Serial-ATA-NEW-/130627089772 seems legit unless I actually need more watts, like maybe 500W?
Edit: Forgot to mention I NEED a microATX PSU since my case is small.

All suggestions/recommendations are appreciated.

[» Magic «]

400w with the 7790 should be fine, best value card

[Frank]

Would this PSU fit you? http://www.newegg.com/Product/Product.aspx?Item=N82E16817139049&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

[blαh2355]

Would this PSU fit you? http://www.newegg.com/Product/Product.aspx?Item=N82E16817139049&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

I don't believe so. I need mATX, my current PSU dimension is roughly about 5"(W) x 3"(H) x 5.5"(L). The length does not matter as much since there's more room before it hits the optical disk drive but i believe the width and height do matter. I see several ones on Amazon that can fit my needs though. What are good/trusted brands though?

[Supertoaster]

I don't believe so. I need mATX, my current PSU dimension is roughly about 5"(W) x 3"(H) x 5.5"(L). The length does not matter as much since there's more room before it hits the optical disk drive but i believe the width and height do matter. I see several ones on Amazon that can fit my needs though. What are good/trusted brands though?

Corsair, Rosewill Hives, Seasonic, PCPower&Cooling, Antec.

Seasonic are the best you can get btw. They make a lot of power supplies for those other companies too.