Asking Advice on wether system may accommodate update.

Hi Community,

I currently have a system at home thats built out of a Asus P5KPL motherboard, Intel core 2 duo e8400, GIGABYTE Nvidia 9500gt with 1GB of memory GPU and some random 3GB of RAM. My question is rather simple, i wish to upgrade my system (even though i can say it still runs most games at medium setting decently) to something newer. As i've been checking most games are not as CPU intensive and don't seem to max my processor out completely so i was wondering wether a GPU upgrade would do me some good. I was looking into such cards as the Nvidia GTX 550Ti but i noticed in some forums and comments that the card requires a PCIe 2.0 and I am unsure wether my motherboard supports it, or wether it does truly need it. Would any of you have any insight into the question? Thank you for any support.
Cheers!

I checked out this version of that mobo (not sure which one you have) because it had the most reviews.

http://www.newegg.com/Product/Prod [...] 6813131288

Doesn't look like it has PCIe 2.0.

My budget would have been very basic, mostly enough to accommodate buying a new graphics card for my computer. But since it wont take it i will most likely wait till the summer to change all my parts so that i could also start off with Ivy Bridge and build from there. Thanks for the prompt replies.
And to clarify the motherboard is this one http://www.asus.com/Motherboards/I [...] ifications
though i doubt it makes any difference.

Thanks for the answers Since nothing can be done and my set-up so far surprisingly, and incredibly seems to run the newer games quite well at higher resolutions and high detail ill continue to save up and wait happily for Ivy Bridge
Thanks