OK you need to ask yourself a few questions here:
1. Will I use memory intense programs that will utilize 2gigs of ram?
2. Do I want to overclock?
3. Do I game? If so which games?
All in all if you aren't using Photoshop, Premiere (or other iffy ram programs) or planning on playing Fear or BF2 I'd say stick with the 1gb you have now. If you plan on overclocking you'll most likely get absolutely nowhere with value ram. Also, in terms of gaming obviously lower timings will give you better fps rates (even though the differences between cas2 and 3 will be pretty small), so if that's what you're aiming for might want to consider that as well.
Hehe I just reread your post after writing all this so since you are planning on using a ram intensive program by all means go for it. The timings are going to provide little hinderence versus the benefit you'll see from the 2gigs in terms of speed of the program. Good luck.