I'm stuck with excel 2003 at the office, I was wondering if there is a way to extend the number of rows to at least a million or two.
Quite simply: You can't get there from here.
You could try to bodge something together by splitting the data across multiple worksheets, but only you will know how well that's going to work.
If you want to go past 65K rows, you either upgrade to Excel 2007 or newer, which supports over 1 million rows (probably 1,048,576 or 2^20) or you quit using Excel.
Edit: I'd like to also reference Pablo Rodriguez's Answer which indicates that Go-OO, an OpenOffice.org variant, also supports 1 million rows. If your macros and formulas can be translated, this might be a worthwhile possibility. Presumably any other OOo variants based on Go-OO (e.g. NeoOffice & OxygenOffice) also benefit from this change.
I would suggest if you have that much data you need to consider moving to a database rather than a spreadsheet. If your version of Office came with MS Access, this is a reasonable solution for the immediate future. If your data continues to grow you'll eventually need to migrate to a different DB because Access eventually tops out as well (around 2GB of data I believe).
We had an issue along these lines a year or so back. I realize your post says you are stuck with MS Office, but I do believe that trying to make that work is an exercise in futility.
We ended up using a linux machine with kOffice. It handled our file just fine. I'm not entirely certain it'll handle MILLIONS, but it handled 45-50k rows fine.
If you need 400,000 rows in Excel 2003 you can open a flat (
.prn, ...) file that has 400,000 rows in it. Excel will allow and create the 400,000 rows. It will give you a lot of warnings about being able to handle it, but I run some heavy duty macros that place formulas in the cells and I have no problem getting it to work.