Sony :: Beefing Up An Older VGN SZ-370P Laptop

I am trying to figure out a way to upgrade different components on this older machine the VGN SZ-370P, which unfortunately is not appearing easy to do.

Searches on this and other forums have either not yielded much results, or some with thousands of pages that I couldn't possibly read, hence my questions here,
apologies if they have already been answered.

The original specs for this late 2006 model are 2 Gigs of RAM (max) , NVIDIA® GeForce Go 7400 128 Meg, and a 2.0 GHz T7200 Core 2 Duo processor, FSB Speed: 667MHz.

I have already upgraded the hard drive to a larger 7200 rpm unit, and re-installed a clean, uncluttered Windows XP system as per this most excellent tutorial,
as well as gone dual-boot with Ubuntu 9.04 Jaunty.

Can the graphics card be upgraded to the 256-Meg model of same (gaming is difficult with 128 Megs)?Can the T7200 processor be swapped for a faster one, and if so with what gains? (like a T7600 Merom at 2.33 GHz, looks expensive at around $250 on eBay)Is there a way to overclock this machine to try and yet squeeze a bit more performance out of it?Will Windows 7 run on it, or are there missing drivers for some of the hardware?

Having invested in accessories like docking station and so on, I would love to be able to get a bit more useful life out of it, as it had been a lovely machine otherwise.