Ordered a GTX 670, please tell me my PC can handle it

Theres no way an i7 Sandy would bottleneck a GTX 670.. The PCIe 2.0 instead of 3.0, reduces the bandwidth, but theres no visible difference.

About the drivers, you will be fine to update your system to the latest NVIDIA drivers before hand, then swap out your current card, with the 670. Don't bother with Drivers from the CD, they are most often out of date.

All you have to do, is remove the power plugs from the current card, and unplug any display cables. Slide the latch on the motherboard to unlock it, remove any bracket screws that could be holding the card in, then just gently pull it out.

Btw, be sure to not remove any stickers from the card's PCB, or dispose the box. I had to RMA my 670 FTW, and having those things still, eased the process.

919han153 - thank you very much for your help! Reassuring and detailed, couldn't ask for more, thanks again  

Everything you listed will work great. What PSU do you have?

I'm running it now   my PSU is 450 (peak 550). I haven't tested any game, should I be worried?

Edit: also my case is so small I barely got it in there, should I watch temperatures etc?

you shouldn't be worried at all but your psu seems abit low watts :\
but i guess it shouldn't be too much of a worry test some games out if you see any problems just take the card out and put back your gtx 550, then save up for a new power supply !  

650-750 watts is good  

Just tested The Witcher 2 for like 3 hours, no problems at all.

But yeah I think I'll be getting a bigger case and a 750 PSU soon just to be sure. Thank you all for the help.  

Your PC can handle it.

As other said your pc can handle it but a bigger psu would be nice for future proofing but other then that your good to go