Careful. Sometimes it's not always a great idea. google about on what they do. As far as I can remember, they are not replacements for each other, but serve different purposes depending on the software in use (can't be more specific than that).
Just installed 3 updates for Net Framework on two XP machines and WU keeps telling me to install them again and again despite successful installation. Anyone else?
Happens quite regular on XP , if you can find the update on your pc you could try un installing-re installing it, that sometimes fixes it, or just hide the update to stop it nagging you , that's what i do,
As for un installing all the net framework, no thanks i won't be doing that, no point if it's installed
Using the .Net Cleanup tool was quite simple and quick to remove all versions of .Net framework, only took about 5 mins to remove everything. It's the re-installing and updates that takes the time. Seems sorted now though.