System upgrade question:

[siber]

I question aimed at those familiar with the inner workings of SH3 and GWX:

I'm currently running GWX on my system. This consists of an Intel Celeron 2GHz processor, 1Gb of RAM and an NVIDIA GeForce FX 5200 graphics card with 128Mb RAM. Everything seems to work ok, with the exception that the whole game slows down somewhat when I get spray coming over the bows. If I enable the 16km mod or extra skins packs etc, the whole game slows to a crawl.

If I were to upgrade one thing in my computer to improve game performance, what should I add? (I'm not expert with computers, but I can switch bits, even though I'm not entirely sure how they work.) New graphics card, extra RAM or do I need a new M'board/processor? Given that I'm a poor student (who really ought to be working anyway instead of playing games) and I'm on a budget, what would the minimum specs of my machine be? What systems do you guys run for perfect performance?

Thanks for any advice!