Any tips on upgrading to USB 2.0 on an old Compaq running XP-Pro?

That suggests a bad PCI card to me.

To isolate the issue, do you have another desktop to test the card in?

Good idea, I’ll check it out.

If the card checks out, you should disable the onboard USB 1.1 ports, preferably through the BIOS. Windows is supposed to be able to support both types simultaneously, but I did not have much luck when I tried to retrofit an old PIII/Win2K box I had lying around. I did eventually get the card to work, but it did not perform well.

I tried disabling the 1.1 ports using the Device manager, but that didn’t help; I even tried uninstalling the 1.1 drivers, still no luck. I guess it shouldn’t matter if XP is supposed to support both versions at once, as you say. I haven’t had a chance to try the 2.0 card in another machine yet. That’s my next step. If I do this, will I need to disable the any existing USB ports?

No.

@Yetanotheruser , this is why I suggested disabling the ports through the BIOS setup. The OS may support both ports, but if the hardware does not, then it won’t work. I would check with your mobo manufacturer to see if there is a BIOS update available while you’re at it.

When I dropped the expansion card into my old Dell, it booted up all right; it just didn’t recognize the ports on the card. That’s why I suspect there is something wrong with the card itself. Do you get any POST beeps when you boot up the puter, or does the freeze happen when it tries to load the OS?

@IchtheosaurusRex It’s a Compaq mobo, and when I boot with the new card, the “Compaq” screen comes up, but nothing more.

It’s not POSTing (Power On Self Test).

I guess the problem could be that the card is not properly seated in the PCI slot, or you’ve put it in the AGP slot (if your computer has one) – both of these would cause the PC not to boot.

I stull suspect that your USB card is duff. The only way to check is to try it in another machine.