Best to remove the wallpaper. Moisture in paint can cause it to bubble and separate. If you need to remove it in the future it will be a bear. If it won't come off use a good stain blocking primer like KIlz then paint.
I agree with William. Remove the wallpaper and the glue from the wall before painting. If the wallpaper is stubborn, pick up a Paper Tiger from a hardware store. This will put tiny holes in the wallpaper, then you can steam it to loosen the paper. If you paint the wallpaper, even if it doesn't come loose or bubble like William said, the wallpaper could come loose later and once you have dry paint on top of wallpaper, it's a LOT harder to get off. Wishing you the best.
http://www2.benjaminmoore.com/en-ca/for-your-home/painting-over-wallpaper Benjamin Moore isn't necessarily the best. If you can remove your wallpaper you really should. It takes extra time but is really a good idea.
If you are determined to paint over wallaper, level out any rips with spackle and sand smooth. If it glossy paper you may want to scuff the gloss off. Prime with oilbased primer, that way you will not reactivate the glue under the paper. Follow up with latex paint.