Let's see.. non-gamer, newer technology.. cheap! i'd suggest a GT430 or a HD5570, i myself have the same card as you right now (8400GS) it won't handle games at high details or high resolutions, but again. i'm not a gamer..
It's weird that the tech could not install the video card, usually that's done in 4 steps:
1) uninstalling the current drivers (by it's uninstaller, then cleaning the leftovers)
2) removing the card from its slot
3) installing the new card on the same slot the old one was
4) boot into windows and install the new drivers.
I'd say that tech is not a tech hehe...
For a non gamer that's what i'd suggest, really