Adding USB cards

I've got an old Compaq XP desktop with USB 1.1 ports and need to add USB 2.0. Can I just get a USB 2.0 PCI card and plug it into the MB or is there anything else I need to know/do (like figure out somehow if the computer can even recognise it)?

I also have an older Dell 98 desktop with no USB ports at all, and I need to add a USB card to it - either 1.1 or 2.0. Same question here.

Thanks!

Good article here http://www.ramelectronics.net/html/usb-howto.html
That should answer most questions you have.

Thank you Ferret. I'l go have a read.........