What graphics card is the best for my computer

[creative_name]

First off I'm only in middle school so my options are limited. I can only get something that's around 50 bucks and from a trusted retailer like amazon.
So my computer specs are
Power supply: 280watts
RAM: 2GB but that will definitely change to 4 Gb (computer is very limited)
Hard drve: 500 GB I think
Motherboard: lenovo one
My computer is the lenovo think centre m58p. It is the very small version.
I was thinking of getting the Geforce210 from evga. But I saw that it needed 300 watts. I have read that it will work fine but I don't think that will happen. And my computer is like 3-3 1/2 tall. The motherboard is a bit raised to. My graphics right now is like integrated I think because it's an intel q45 q43 express chipset. So I'm hoping I can get a cheap dedicated one.
My main purposes are to tak some load off my processors shoulders(intel pentium xeon III E4800 running at 3.00 GHz).
Another purpose is to play Microsoft Flight Simulator at around 30 fps(right now it runs at around 15 with no traffic, no light bloom, medium high airplane graphics and no water details).
So what graphics card can be compatible with my limited computer?

 

[amuffin]

This is a little bit hard to choose, considering your computer specs and your budget. But the best bet might be a radeon 5450.

 

[djrabbit]

I have the Evga 210 and it runs fine with 250 watt for me. It will not run any new games though.