Use PM to prepare drive and install XP, then install Bootmagic (come with PM) to manage
which one to boot up.
You can get PM8 from Amazon for £20 click here
But, I think the better way to sort out modem problem. It should work if you install correct driver software. I think you download it from BT website. Or get a new modem, ZyXel Prestige 630 USB ADSL Modem £21.62 click here