Here's what you're probably best off doing:

Since you're just starting out, there's a good chance you'll quit. Even if you don't, you'll almost certainly reach a point where you decide that you want to sound like yourself and not Sum 41. Also there's the comfort factor: I love Incubus and Dirk Lance's bass tone, I also love Norwood Fisher from Fishbone. Both of them play Warwick basses. I've hated every single Warwick I've ever picked up and played. Great tone, but I loath the way the strings are spaced, the setups, and the feel of the neck.

Anyway, back to the topic at hand...
You're probably best off going to a guitar shop, walking over to the used rack and trying various guitars. You'll probably want one with humbuckers for the kind of sound you're looking for, but try as many as possible. Find one you like the feel of and sounds good to you. Buy an amp along the same lines. If you buy both at the same shop at the same time, they'll probably cut you a deal.

Best of luck.