[SebC]

For XS vs. XSi, if you don't want to move up... the key features for me would be: compatible with remote (useful for tripod, night shot type stuff), spot metering (for tricky exposures), and highlight tone priority (to retain highlight detail).

Edit: so I actually clicked through your links, and now have a bit more to offer.

IMO the difference between, XS and XSi is not that much. Generally I'd go for the one with the extra lens. Now having said that the extra lens is not that good. Generally, if your gf likes landscapes and such, the 18-55 is much more useful. 35mm equivalent is 29-88... 28 is what you'll find on a "wide-angle" point and shoot, 35 is typical for wide on a point and shoot, 50 gives a natural perspective, 75 is portrait, 88 at the telephoto end it's a 3x zoom. 75-300 will give you 120-480 equivalent which is pretty much more zoom than you'll ever need unless you're doing highly specialized wildlife or sports stuff. Thing is, the more you zoom in the more you want a lens that has image stabilization, and this lens doesn't have it. It's also f/4-5.6, which is a relatively slow lens. Basically, this lens needs a lot of light and will be difficult to use without a tripod. So really it depends on what your GF will shoot. If she's technical enough that she'll work around the limitations of the 75-300 go for it, otherwise, get the XSi. Or get the XS without the extra lens, and save 100 bucks for a good IS zoom later.