The 8700 appears to have a single PCI-E x16 slot, so it should should be able to handle your video card without a problem, though you wouldn't be able to add a second card and SLI. The included 460 w power supply is probably good enough for your card, presuming that it has the appropriate output cables for your card. Otherwise, an 850w supply is more than enough (Dell used to use proprietary motherboards and power supply connectors - I believe they are now industry-standard).
Mike