I just installed SL on my fiance's 10v. Got the 16GB SSD
, and after installing the base system only, there was still ~8GB free.
MS Office is gonna take up, what? 2-3GB?
iLife is a good 4GB if you include EVERYTHING (but do you really NEED Garageband on the thing?)
iWork is only about 2GB for the complete suite
I would recommend getting an external HD, and then moving what ever apps you don't use on a regular basis onto the external. It's amazing how modular everything is in MacOS and how painlessly things can be moved around.
I installed the iPhone SDK for her--a whopping 5GB--but after the install, I moved the entire Developer folder to her external, recovering nearly all the used space. Did the same with iLife (kept iPhoto local). iWork stayed on the internal.
After all that, she still has 3GB free. And I didn't even run Monolingual, which would probably free up a gig or two.
In my opinion, people who opt for the larger drives are missing the point of the Dell Minis--they're NETBOOKS. They're not SUPPOSED to replace your primary computer, just supplement it. It's the people who expect the thing to do everything their normal computers can that end up disappointed and returning the things.