I use a Livebox with a desktop, two laptops (all Vista) and two netbooks (XP), so there is no reason why you can't use one with your Sony..
But have you checked other possible causes for the slow connection. The speedtouch may have a problem; the cable may be damaged etc.etc.
But in any event I would get a Livebox and a wireless adaptor for you desktop. Saves a lot of messing with cables.