I agree with the PPs that said don't worry about spending money on Microsoft Office...google docs works great and you can download free versions of Office (google 'open office'). However, your district may have a district license for that software, so you might not even have to worry about paying for that.
I would suggest a projector, smartboard, document camera combination. The teacher(s) using the lab will want to be able to show the students on one large screen before setting them loose to work on their own. If you can not afford an interactive white board (smartboard, promethean, etc) at least get an lcd projector because you will be able to display webpages, they just won't be interactive.
Kidspiration is a fun program, but there are so many 'free' things on the web that will do similar things. bubbl.us is one example..and imo, much easier to use with little to no training.
Invest in good headphones that have the microphone built into them. (They kind of look like the headsets that 911 operators use..that is what my kids say, anyway

). They may run you about $20 each (although when you buy in bulk you may get a discount), but they will be well worth the investment because you will be able to record (podcasting) as well as listen.
Good luck! What an exciting thing!
PS..I guess I should have asked...is this a mobile lab or a stationary one? I assumed it was stationary.