Getting Work mail from home with Vista?

I bought a new Inspiron 531S a couple months ago. Everything seems to be running fine.  The only annoying thing is that I can no longer check my work email from home.  I have 3 other machines nearby running XP - and all of them can log on to the network at my work. Why doesn't vista?  I checked with my network guy to see if the system wasn't compatible with vista yet, and he says that isn't the problem.  I have shut off the security/firewall temporarily to see if that would let me in, and it doesn't help.  Any thought? Settings I need to change? Thanks.