I'm trying hard not pass judgement on existing hardware purchases and decisions, that's another thread
Unless money is no object, or there is a specific gaming issues you wish to address, I'd think you best be served waiting a couples months (very rare I say this). Your suggested upgrade is from middle-high to high of the current generation of GPUs. Unless you tell by you're game at 2560x1600, eyefinity, or 3d (where Sli/Crossfire would barely cut is) I wouldn't be too concerned with ths minor graphics upgrade.
If you're itching to spend money, replace the 6100 with a 8320 and overclock, or investigte water cooling options (sweden, snow? don't know). In 3-6 months we have better idea and the new lineup, and all the old choices will be much cheaper.