Regarding .NET Framework 3.5 SP1, as far as I know there are no compatible patches. It is installed automatically when you update Windows XP (important and optional updates), so I don't know whether you can safely remove it. Please note that this is my personal XP update list. It has been tailored to my needs and I don't want to put too much effort into fitting it to other people. So there will be no Silverlight and .NET Framework 1.1 updates listed. Btw, you should also consider installing Microsoft's EMET tool. I have added a link for that.