CPU + GPU

u will be fine with 8800gt..  
about CPU, stay with E6750.
I don't know, i think u will be safe if u aren't buy overclocked cpu/gpu.

The 8800GT is still a useful gaming card as long as you keep the resolution within reason-Do not expect it to run Crysis at maximum settings on a 24" monitor! And it is faster than the HD4650:

http://www.tomshardware.co.uk/geforce-310-5970,review-3...

ATI and Nvidia have different ideas as to what a 'shader' is so the raw numbers cannot be simply compared with each other.

You'll find the E6750 is a better CPU than the E3200, but make CERTAIN your motherboard supports it-Check the makers website, they usually have a CPU support list for their products, old and new.
Take a look at the Overclocking Forum for more info on the subject but if you want to push past 3.2 GHz you'll need an overclock friendly motherboard and a good cooler, regardless of which CPU you are torturing;)
I would never advise anyone to buy used electronic components, much less from E-bay, the risk is too great for my cautious nature, but if you must buy from E-bay, then check the sellers feedback carefully. If anything looks amiss, walk away, getting your money back can be very difficult and in some cases, impossible.

Both things you are considering are great.
GPU is really good and it will play most titles smoothly

CPU is also good, If you are also going for a new motherboard, I suggest you to look at any sub $100 1156 motherboard with a i3.


GOOD LUCK

The shader units used by Nvidia and ATI are entirely different creatures and cannot be compared based on a simple count. An 8800GT is much better than an HD4650.

Thanks for the reply. I've read the e6750 has more L2 cache than the e3200 but it can only be overclocked to 3.8, the e3200 can go up to 4ghz. Will I get better real world performance from the e6750? I haven't every actually overclocked before so I'm only going by what I've read. I personally might not be able to overclock to either of those speeds.

My budget is limiting me to an e3200 and 4650 new or a used 8800 and e6750

Good to know.

Motherboard definitely supports it, gigabyte g41, it's got overclock options and I've chosen a xigmatek, both have had great reviews, I've researched hunners on overclockers.net already!  

I was hoping ebay could make my budget go further, but I'm new to overclocking so was wondering how this affects a cpu/gpu lifespan? I've heard the scare stories of them catching on fire but they seem few and far between. I'm still tempted, I'm thinking if it doesn't die in the first month then it probably won't. Can dabs/scan/newegg tell if a cpu/gpu has been overclocked?

Glad to see you're doing your homework! Getting the right parts now will save a lot of trouble later.
Overclocking will shorten the lifespan, but how much depends on: How hard you push it, how good the cooling is, how many thermal cycles it will go through (how often you turn it on and off) and just plain luck.
As a rough idea, my E6600 at 3.4GHz about matches my i5 750 at stock speeds according to the benchmarks I've run-Real games not synthetics BTW-so the gains are very real.
Not sure about your last point but AFAIK yes, they can tell. Graphics cards have registers built into the BIOS (not sure if its in the hardware or software) and processors also have hardware registers built into them. Of course I could be wrong...Anyone else want to clear up this point?

Sold! Ill get a new e3200 so that I can at least aim for 4ghz!

I'm looking at ebay for used 8800's, I've read that gpu's can't be pushed that far so it's a safe bet.