Laptop with Sound Studio Capabilities

I’m not sure if “Sound Studio” is the right phrase, but I’m in the market for a new laptop. I want it to be good enough to run Flash, Photoshop and Dreamweaver, but I also want to be able to take it with me pretty easily. In other words, it’s not a desktop replacement. One of the reasons that I want to do this is that I want to start working with music, and be able to input music straight from guitars and microphones. Just like you would plug them into an amp.

I know I need special plugs and stuff to do this, but what software would I need. I also need some help deciding which laptop would be right for me. I was thinking maybe an iBook G4 with Garage Band and an external portable USB preAmp kit. But I’m not partial to apple products. What do you guys think would be a suitable laptop for this?

I don’t have a very big budget, so I’d prefer if I could get this for under 1500 bucks.