Well, the first potential problem I can see is, as far as I can tell via the research I've done, is the card. Officially, this card is supported to run the game, but it's not suitable for playing Sims 2 and can give her problems. One other note is the Sims 2 requires a card that supports DirectX 9, I believe, and hers supports 8, (according to the documentation I've read). It's also worth mentioning, according to
this list here, her card is no longer being supported or updated by nVidia, which means it can be considered obsolete.
I would suggest, if it's in her budget, to consider an upgrade.
This is a good article to refer to and, you'll notice, her card isn't even listed there. Reading further down the article, where they talk about the individual requirements for each EP, they confirm what I have said above about the suitability of the card for running the game. For Pets, the minimum video required is a 32mb card, true, but that number is really far too low to run the game adequately. I would recommend nothing below a 256 mb card be used.
It would also not hurt at all to upgrade her RAM, if possible, to at least 2 gb, if her motherboard supports it.