@nycbigl We only ever got the beta version of CAW, so it's not surprising that the program has so many issues. (For example, Steam users have to edit their registries to make it work at all, which is not a lot of fun.) It's also not something I'm familiar with, so I just fall back on the troubleshooting advice of others with more experience on the subject. Still, if I ever see a reliable solution to the EIG problem, I'll make sure to pass it along to you.
As for your graphics card, it's older and will need extra care. One of the biggest favors you can do for it is turn down your graphics options, particularly water and high-detail lots. I have a reasonably strong card, and I keep those at mirrors only and 2, respectively. But you might need to lower the other options as well.
I'm also not sure that your card can handle the stress of Pets and Seasons, or even ITF and IP. Those packs demand a lot from graphics cards, and even the lower-level dedicated ones can struggle to keep up. Again, every computer performs a bit differently, but yours isn't really built for graphics-intensive gaming. If you really want to play with these packs, you might need to use only one at a time to protect your system. Hopefully it will hold up and perform well enough for you to play TS3 the way you want.