New laptop for work. Need suggestions.

[BLINGMW]

I need some help with a 3 year old Macbook...

I can do this kind of stuff, and you probably can to. What I'd recommend though is upgrading her internal HD to something larger for like $75, having half your daily stuff on an external is annoying, and her 3yr old internal drive will catastrophically fail some day anyway. Check dealmac.com for components.
Does she currently have a backup drive? If not, she may not realize she needs one. Again, $75 gets you a 1gig external that she can plug in now and then keep her stuff from disappearing one day. Time Machine actually works pretty well, not a whole lot of features and options, but it's also easy to use and reliable.
The OS upgrade is easy, but backing everything up to that external would be nice first.
There's not much "refresh" to be done that the OS upgrade won't do. She might need some more RAM though, especially if she has something less than a gig.
I'll be happy to help if you have any questions, send me a PM and I'll give you a call

On an unrelated note, and I don't think anyone asked, but for anyone shopping, I have a laptop to NOT recommend. The ThinkPad W510.

Our office went to the W500 and 510 series this year, and the smaller X200 and 201 for the road warriors. The 200 stuff seems just fine, well built, few failures. But these 510s that seem to have decent reviews online, and it's a i7 that should be a nice desktop replacement? They're CRAP. Every single one of us, within a few months of getting one, has had a problem. HD failures, the docks are crap and many have been replaced (mine is pretty touchy too, but for fear of getting a worse one I haven't complained), mine wouldn't get passed the initial black boot screen for a whole day (it chose to do this when I went to california), my co-worker's takes 10+ minutes to start up and no-one knows why, another's speakers blew. The keyboard is poorly anchored (design flaw) and the whole thing is so heavy it feels like it's going to fold in half under its own weight when you pick it up. Maybe since I'm a mac guy my standards are too high, but I'm seriously thinking about requesting my 5yr old Dell back. It didn't miss a beat in 5 years. Only reason I got a new one was because it was getting a little to slow and didn't have enough RAM to deal with all the spyware our IT department installs.