I have a Yikes tower with what seems to be a flaky USB port. The hub, when plugged in, exhibits much weird behavior. When the keyboard is plugged in alone in either port it occasionally acts strangely also (repeating alert chime). IIRC, this machine has two ports sharing the USB bus, so it seems to me like that component may be starting to fail.
Luckily, I can pop a USB card in to a PCI slot and not worry about it.
Can anyone recommend a good vendor for USB PCI cards, and a good place to buy it?