Which System to sell

So I'm having a bit of a financial crises. I have essentially, two identical systems - One I intend to offer for sale:

1) Intel Core2Quad Q8400 based system
2) Intel Core I5-760 Quad-Core system

Both systems have 8 GB of RAM. The Q8400 based system has 4x2GB of DDR2-800 RAM. The I5-760 based system has 2x4GB of DDR3-1333 RAM. The system I sell will get an AMD Radeon HD4650 (not much, I know). The system I keep will inherit my Geforce 8800GTS-640. I'm not much of a gamer now, but I am looking at Borderlands 2 and Mechwarrior Online and a graphic card upgrade (GTX670) when finances are back to normal.

So my questions are:
1) Would I really notice any difference running an 8800GTS-640/GTX670 on a Core2Quad Q8400 system as opposed to a Core I5-760 based system (1920x1080 resolution)?
2) Would it really be easier to sell the Core I5-760 based system over the Intel Core2Quad G8400 based system? Assume a $350 price point.

I'm not really going to go into specifics at this point, but I'm looking at selling:

-Rosewill Case
-Antec PSU (capable of running a Geforce 8800GTS-640)
-Gigabyte H55M-S2V motherboard w/Intel Core I5-760 CPU + 8GB (2x4GB DDR3-1333) RAM
or
-Gigabtte GA-EP43-UD3L motherboard w/Intel Core2Quad Q8400 + 8GB (4x2GB DDR2-800) RAM

Let me know your thoughts.

Thanks
-Wolf sends