If you were ready to drop $190 on the 1100T and don't want to change anything else, I'd get the 980 for $20 less.
The FX-4100 is ~$70 cheaper and should perform around a 965-970, but you would need an AM3+ motherboard.
Going from the list above, personally, I'd go:
-$70
AMD FX-4100
-$70
MSI 990XA-GD55 AM3+
+$10
Rosewill Challenger
Was going to suggest an upgrade to the video card, but you seem to be missing some things:
+$21
Sony Optiarc 24X DVD/CD Burner
+$100
Windows 7 Home Premium 64-Bit OEM
Also, Solid State Drives are much faster, but also quite a bit smaller for the same price.
Do yourself a favor, go to My Computer and right-click on Local Disk (should be C: ).
If the used space is 60GB or less ignore this, but if its quite a bit over 60GB I'd suggest a regular mechanical hard drive for more space.
I'm just looking at this as a totally new build.
If you're re-using the hard drive and DVD/CD Drive in your current computer feel free to ignore those suggestions, though I assume you will still need a new copy of Windows 7.
