Is this a good system for gaming?

I'd personally be reluctant to buy a computer from ebay. Regardless of that, the graphics card in that system is weak. The processor is ok, but you'd need a new graphics card if you want to play anything recent on even medium settings.

No its not you main problem with that system is the GTX520 graphics card its not for gaming at all.
Whats your budget?

You would of been better off with something like these....
http://www.ebay.co.uk/itm/261047153011?ssPageName=STRK:...
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=26...

I would go up to around £350 for a decent PC, though ideally £300 or less. Thanks to both of you for your replies!

Well if your in the UK, keep an eye on ebay for a PC builder called togden57, as they regularly sell good systems that are a bit out of date but can still play games.

Out of curiosity, is this PC any good? Was thinking about bidding, but the low price put me off.

http://www.ebay.co.uk/itm/Powerful-Gaming-Tower-PC-Inte...

Its a better one than the other but still a weak GPU.

Can you not self build ?

What games would that particular PC be able to run well? I said I was thinking about bidding. Truth is I bought it just now without thinking.. binding contract n'all. Hey ho.

Add this for £89 http://www.aria.co.uk/Products/Components/Graphics+Card...
and you will have a good gaming PC. Get a good cooler as well and overclock past 3GHz and you could go for an even better card.

I'll definitely look into that, though without them upgrades, what do you think it would be able to run?

The PC is old (2007-2009 roughly) but was very high end then. You should be able to play any game its just what settings you can play them on. The CPU is still strong especially if you get it over 3GHz but the graphics card is quite dated now.

If I were to add the graphics card you recommended, how well would that boot its performance?

You would be able to play all games on high settings @ 1920 x 1080 and most on ultra settings

If that's without overclocking, is there really any need to do it? Thanks for your help!

Not really if you wanted to get a better graphics card it would be, it would also help in CPU intensive games, like large multiplayer maps on BF3.

better look elsewhere and increase your budge. get an intel quad core if you want to play bf3 with anything near smooth fps. also look at a minimum of a gtx 270,gtx 450,gtx 550 or similar performing ati cards.
the fx 4100 is a dual core cpu in real terms. yes it has 4 cpus but there paired into modules. so they are comparable to a dualcore cpu with hyperthreading. which will be no good for bf3. you will get little more real world perfomance than the old 775 dualcores. so a pointless buy for bf3.

to play bf3 the minimum you need is a 775 quad core of 2.4 or faster
or a amd am2 quad core of 2.6 or faster.
4 gigs of ddr2 800 or faster.
a gtx 260 or ati 4890 or faster.
if you pick nvidia you want a minimum of a (x50 1s you get past the gtx 260) x60 x70 or x80 x90
for ati you need to get a x750 x760 x870 x690 perfereably the higher the fist number x the better for the lower numbers preferably 6 or better.

I was talikeng about the second ebay PC with the 775 Quad CPU @ 2.4GHz + 4Gb 800MHz RAM that is the one you bought isn't it £148.68 + delivery?

Yeah, I bought the one I linked from Ebay

Then as I said and Hexit confirmed (though didn't see the spec you got) with the 6850 you should be able to game very well.

and it's fully compatible?

Is what compatible? I think the answer will be yes though.