2 memory card readers = very slow boot

Hello, first time poster - please be gentle!.

I've got a home-built system based on an old Viglen motherboard. I've set it up as a multiboot system running Win XP, Vista, and 7.

I recently discovered I have a second 9-pin internal USB port, so thought I'd add a 2nd card reader (mainly because the old one doesn't support SDHC)

However, since I did so, the boot times have gone from 1 minute to 3 or 4. It now spends 30 seconds just on the OEM screen, and hangs for around 2-3 minutes on the "starting Windows" screens. This happens regardless of which OS I choose.

I've tried unplugging the card readers, and it's fine when I only use one or the other, the problems only happen when both are used at the same time.

Any ideas anyone? It's driving me mad!