If you're interested I can link you to the components you would need to get the basics of a LGA 1150 or AMD AM3+ build going, allowing you a ton of upgrade headroom while maintaining or increasing your current performance. It can be done at $300-$350, yielding you a budget processor that can be upgraded later, but that is already better than what you have now. You would go with lower GPU and upgrade down the line, but it would already be better than what you have. The only catch is you would need to re-use your case, HD, and optical drive. Also keep in mind an OEM version of windows would not reactivate on this new motherboard (Meaning you shouldn't do this), only a retail copy will allow you to reinstall once you change it. Would you like to try?
If not, I'd say scale back on the GPU. It should work as the motherboard is a pcie 2.0 slot, but again it won't be fully utilized if you buy the 750ti, so it's wasted money if you're not upgrading the rest any time soon.