I am possibly in the market for a laptop computer (or do they call them notebooks now? I'm such an old fogey!

). The reason is because my school district requires that we use a very specific formula for calculating grades--e.g. Language Arts grade is 45% Writing, 25% Grammar, 25% Spelling, and 5% Handwriting, with 10% of each of those subsections being for homework grades. There is no way on earth I want to figure that by hand, and for various reasons I can't really do it on a spreadsheet.
I have used a fabulous program called Classmaster to figure grades in the past, and have ordered my $72.00 copy, which will hopefully be delivered soon as I have to figure progress reports this weekend. (Darn this six week grading system! It's fricking August and I'm doing progress reports!!!)
The problem is that the district does not allow you to install ANYTHING on their computers. They also do not allow you to bring any computer systems from home and keep them at school. I could do the grades at home, but then I wouldn't have them at my disposal if a kid had a question or had an impromptu parent call asking about their child's progress. The only solution I (and others at my school) can figure is for me to get a laptop and carry it back and forth, which is allowed.
So I'm asking for your advice. Are there any features I should know about? Things to watch out for? Models or brands you can recommend to get or avoid? I really can't afford to spend much more than $1000, and I won't do any of those 3-year internet deals or anything.
Thanks much for any advice or thoughts you can offer!
Cindy