but i just noticed it says "PCI Express 2.0", which probably isn't included on my P5B Deluxe Asus mother board, which i bought 3 years ago...
Wikipedia says they are backwards compatible, but who knows if that is true
I just ordered tonight and it's not too late to change my mind...
will this card work with my Asus P5B Deluxe PCI-e x16 card slot?
More aboutradeon 4870 asus
It's fine, don't worry about it.
The card will work just fine; PCI-E is indeed backwards compatible, so you don't need to worry. Make sure you uninstall the drivers from your current graphics card before installing the new one and you'll be fine.