Help with buying a new GPU

[TroyHopson]

Well, I am going to upgrade sometime soon to a new, better GPU, clearly.
I bought the PC pre-built, and it was quite a nice rig for the money. Only about 650 total for the PC itself.
I'm going to install the components myself, but need to know if they are compatible, as I know installing a new GPU and PSU won't be very hard in itself, but making sure parts are compatible isn't the simplest thing in the world.
Specs are as follows:
-Motherboard: ASROCK H61M-HVS, uATX Intel H61
-Processor: Intel Core i5-3350P 3.1GHz
-Hard Drive: 500GB SATA II
-Current GPU: NVIDIA Geforce GTX 650 1GB
-Current PSU: 400W

I have the GTX 650 1GB, and find its performance great... However, I want to upgrade to a better card for even better performance for better FPS and higher settings.
I have been looking at a HD 7870, specifically: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125418
And I know that the horribly underpowered PC would need a power boost with the power hungry 7870, so I was looking at a 650W: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005
Looking at my current specs, would the Radeon be compatible? And are there any other GPUs I should look at for the same price (or lower) as the 7870? I have heard the 7870 is pretty awesome.
Thanks

 

[mbrown138]

From what I know, a 650w psu should suffice. AMD reccommends at least 600 so your choice is good.
Your mobo has a PCI 2 slot but from what I have read it won't matter.
For a few extra dollars, the 7870 GHz should do nicely for your build.