I think your PC can be ok for a bit yet - your cpu is still solid enough
(see link:
http://www.tomshardware.com/reviews/...ck,3106-5.html ) - the turbo-boost feature can I think take one core up to 3.6 GHz [and there's always overclocking further down the road], 4GB ram is fine. Try it with a new graphics card first. You can always transfer the card to a new updated PC later if it still doesn't cut it, but at your resolution a lot of cards should be ok.
I do think (!
) that the patch will be with us in weeks. Personally I've been thinking of upgrading my own videocard for a while as mine doesn't cut it well with COD either. I've put it off for the last 6 months because I spent a silly amount of money on a new hi-fi, then news of the new cards from ATI and nVidia led me to wait that bit longer.