you know how macbook's have the built in little camera that enables a live feed to come through their little picture capturing app?

i am looking to set up something like this on a pc...tho what i want is more flexible/powerful.

basically i want to use a digicam on a tri-pod - a hi def one and run the signial into my pc and into software that can run realtime filters so that i can see different effects on the feed coming in. then i want to record the hidef/processed video signal to hard disk.

what hardware + software (in addition to my dell 3 ghz p4 desktop) would i need?

i do not yet have the digicam either so please advice if there's anything i need to consider about which camera.

and let me know if my question needs any clarification. thanks.