Lots of places have an MS mindset, or simply do not want to bother with Linux/firefox etc.
Never just take their word for it, always give it a shot first.
As mentioned above, sometimes it's just a matter of changing a setting in FF to fool the webserver, or adding a plugin.
As for the Office stuff, you should have (or can add) OpenOffice (free of course) which is highly MS Office compatible. It's not perfect, but then different versions of MS Office aren't always 100% compatible.
Again, suck it and see.
Keep posting qns (with details) and we'll help if we can.
Herer's some good links: