Youre in Canada so you can't get any of those. And you DO NOT NEED A NEW PSU.
A 220,430, 440 520 all work just fine on a 300W power supply and the 440 is roughly a 8800gt in specs so it should be good if you actually did want to game.
The 440 can be had for as little 59 bucks at directcanada.com and ncix.com after the mir, the other cards are even cheaper.
Wow, this 430 is a great deal
Newegg.ca - XFX GT-430X-ZAF2 GeForce GT 430 (Fermi) 1GB 64-bit DDR3 PCI Express 2.0 x16 HDCP Ready Video Card
So you ca get great cards and not have to get a new psu.