As a drummer masquerading as a guitar player I can tell you that timing is everything. You can be the most amazing soloist in the world but if you can't keep time and play along with others, what good are you? Same thing applies to drummers. The most amazing thing about John Bonham was that he rarely if ever stopped keeping time with his foot on the high-hat even through some pretty tricky fills. The man had impeccable timing and is one of the reasons Led Zeppelin was such a great band, but I digress...
The only time I tap my foot (or stomp with a glare at the drummer) is when the drummer is dragging or all over the place. In other words, if the drummer or something else (metronome) can maintain time for you, you just need to focus on playing along in time. Even if it's setting up a simple click and playing eighth notes on the low e string. Once you get that down, practice accenting the note on different beats (accent on the 2, accent on the 4 etc.) Playing along with the ipod is a good way to practice it as well. So you don't need to be able to tap your foot to play in time. You just need to know the guitar part well enough to focus some of your attention on the timing.
