Exchange versus Groupwise

My company is thinking about migrating from Groupwise 6.0 to Exchange. I have to prior training in Exchange, so I am reluctant to suggest this as a viable alternative. We have recently been having problems with our GWIA which prompting the change, but also there are grumblings about getting a Blackberry server in as well. I know that in the past Exchange has been more susceptible to viruses and that it can become unstable and therefore need to rebooted alot. Has anyone made this migration lately or do you have an opinion on the matter.