You shoud probably use the search function here and read the various posts on this subject - and make your own conclusions. I read and read about it, felt good enough about how to tackle the job and completed it. Now am faced with some issues. After reading responses to my current problem, chatting with others and calling paint reps, I am uncertain how I will proceed.
I'm not saying that it can't be done - or shouldn't be done - but you should probably get real informed before tackling this just in-case you're one of the unlucky ones ... like me.
I cleaned my walls with TSP and thoroughly rinsed it, sanded the surface, applied XIM primer and top coated with Sherwin Williams Duration Laytex. The XIM primer was pretty difficult to work with IMO. All seemed peachy for a few months. Then (see this post): http://www.airforums.com/forums/f39/paint-went-tacky-55249.html
Good luck to you. I'll continue to update my post when I figure out what I'm going to do. I did see a product on the web made specifically for coating vinyl wall paper (Resene Vinyl Wallpaper Sealer - Prevents Sticky Finish
) but I can't find anything available in the US. It wouldn't resolve my problem anyway - since I've already primed & painted. Doh.