What do you mean by upgradable for your daughter?
As with any Dell you can customize computers. You can also pretty easily upgrade RAM on a laptop, anything else is a little more tricky, but some can be done with not much hassle.
The Mini 9 does have real barriers in the maximum 1 Gig RAM and 16 Gig Solid State Drive. There is also a Mini 12 that has prettu much the same specs but a 80 gig HDD. They are light, small and otherwise very suitable for online applications. They will run Open Office or MS Office off the main disk, but since you have the limited disk space ( on the 9) there is also the option to run portable app version of Open Office from a USB flash drive.
Otherwise the entry level Inspiron models will all meet your needs. I have never really looked at the studio models, but as far as I can tell they seem to be slightly over priced 'trendy' versions of the comparable Inspirons. I could be wrong on that though.
They have a new 15.6" Inspiron that has 4 Gigs RAM and 250 HDD for $599, and a 2Gig RAM /160 HDD from $479. If I was in the market for a new school laptop, I would almost certianly be getting one of these 2 models.
http://www1.ca.dell.com/content/prod...ref=lthp&s=dhs
Minimum you need 2 gigs of RAM to run Vista + apps without feeling like tearing your eyes out, however since the video card shares the system RAM, I could see an argument for 4 Gigs, especially if the price is right.
As for good wireless, there really isn't much you can do in terms of upgrades that do not also depend on the network you are using them on. For example, you could get a dual band wireless card which has been shown to increase your network speeds on crowded access points. You could also get a card that supported 802.11a or 802.11 draft n wireless. Since most stock laptops only come with 802.11g, the g bands on public wireless bands on campus are extremely crwoded compared to the other bands (if available). Thats the real kicker here, if her school doesn't offer 'a' band wireless having a card that supports it will do nothing. Chances are no school will commit to hardware that supports 'N' untill it is standardized, so any use you would get out of a typical N card would be either on your home network, or by utilizing dual band features that the higher end cards tend to have.