What exactly will you be using the laptop for?
If you will just be tracking, do you intend to record more than 2 tracks? A usb 1.1 audio interface will not cut it if you intend to track more than stereo in/stereo out. Either get a usb 2.0 audio interface, firewire, or a pcmcia soundcard.
John is right about HD speeds. You need a fast HD if you intend to multitrack or stream a LOT of samples from HD. Additional ram is only important if you are using ram-based samplers or romplers that load to ram.
The Ozonic is a usb 1.1 audio interface/midi controller. If you intend to use your laptop as a synth, it better have a really fast cpu, and if you're streaming samples, a 7200 rpm HD and lots of ram. Softsynths and samplers are not for the faint of (giga)hertz - I have brought a 1.8 gHz machine to its knees just playing 4 notes on a sampler. (Then again, those were very PHAT notes).
Have a go at musicxp.net on how to optimize WinXP for music.