I am rhythmically challanged....there is NOTHING more frustrating that learning a solo or a passage of a song and then finding out that the rhythm is off and you have to re-learn it. This is often more difficult than learning it correctly in the first place.

If you want to be good, always use a metronome. Learn the whole thing together (rhythm and notes). It will make your life and your music much easier. Start slow and work your way up to speed.