I have a variety of boot options (various flavours of Linux, mainly) and when I use Linux for browsing it's a different world. Snappy, responsive internet, fast scrolling through pages etc.
Does this sound like virus/keylogger activity? I'm not seeing any unwanted popups or odd activity on my router or modem, but something has drastically slowed down the responsiveness of my XP partition. I guess it's out with the old Spyware detectors and see what happens. Any ideas most welcome...
As an example of the difference, here is a Speedtest from XP:

and here is one from Linux, taken about 5 minutes apart:

However that difference doesn't give a true picture of the difference in 'feel' between the two. Everything internet-related on XP is subject to a real lag, whereas Linux is sharp and responsive.
Oh yes, and I've already tried re-installing TCP/IP on XP - no difference.