I have a Sitecom 4-port externally-powered USB 2.0 hub and a D-Link DSL-200 USB modem, plus other USB peripherals. XP sees the hub OK and requires no special drivers.
Sometimes during a reset and always during a power-up after the system had been switched off for more than a minute or so the hub port to which the modem was connected would die (no green light). In that state the PC would hang when it was checking drives during the power-up or re-start cycle.
If I disconnected the modem or hub and restarted again, all would be well. Then plug in the hub to its usual port, and then the modem to the hub and all ok.
Through a bit of trial and error with various port combinations in dealing with the above, I have come to the conclusion that XP likes all USB ports (ie, including those on the hub) to be in full working order before it will proceed with the boot sequence. Otherwise it hangs at the IDE drive check. (At least, that's what it did on my machine)
I reconfigured my USB port usage - put the modem directly onto one of the PC's ports and other USB peripherals onto the hub. No problems since then.
There are other unfavourable peripheral/hub combinations, depending on both the hub and the peripheral. My Canon scanner only likes Adaptec hubs, so it too has to live on a PC port, not my Sitecom hub.
Read your USB peripherals' documentation. Some say that they cannot be used with, or not guaranteed, on a hub, a la the Canon scanner. If you're using one of those on your hub it may be causing the problem, in which case, put the fussy peripherals on a PC port if you have one.
Follow Richards advice about booting with the hub connected, but nothing hanging off the hub.
Then plug your hub-friendly peripherals into the hub, and your fussy peripherals into any remaining PC ports if you have them. If you don't, you have a problem.
Hope this helps.
AA