Audio Recording on M1330 - Questions/Help

Okay so i have an XPS M1330 and have started using it for some Audio recording using a USB Audio Interface and software called Reaper....

It runs pretty well however every now and then i get some Latency issues...and after checking the system performace i noticed that both CPU and RAM were maxing out...

So.. i hava been thinking of ways to improve/fix this as its the only thing my laptop is struggling with at the moment...

1. Install more Ram... currently on 2gb thinking of upgrading to 4 or 6 with the BIOS update however not sure if this will help my problem... i think audio recording relies more on CPU then Ram? Can anyone clarify this?

2. Downgrade from Vista Ultimate to XP Pro 64bit? - dont really want to as im finding Vista great, but will the PC run faster and have less latency with XP?

3. Install OSX? - might sound ridiculous... but will that make things faster?? Or dual boot OSX just for audio recording?

4. Upgrade to a Firewire Interface - probably out of topic now but thats faster then USB so might put less stress on the CPU??

5. Upgrade the CPU? - currently using the standard 2.0ghz... what is the max i can upgrade to and will i notice much difference?

Thanks SO MUCH to anyone who can help! Really stuck on this one...

and BTW, yes i have played with latency settings and tried disabling drivers to increase performace but nothing works!

I want to be able to use this LIVE with my band but fear it will glitch or crash on me.