What do you think?

Once 70-291 is out of the way, for an elective I am planning to hit Exchange - I am not sure which version to go for though.
It seems logical in a way to go straight to 2007, however I am worried about skipping 2003 since many companies still use it.
I found out yesterday that 2007 does not support public folders either!

Seemingly because Microsoft are pushing SharePoint - $$$$$$$$
It is also 64bit only! Besides a unsupported 32bit testing version. Which makes me think that some companies will think twice before upgrading.
Our Exchange implementaion cost the company £330,000 ($660,000) - £50,000 was for Symantec Enterprise Vault - I am not sure how we got to that figure??? This was all before I started working here. Either way - $$$$$ - In fact, I am going to double check that on Monday - surely it could not have cost that much?
FYI - 2400 users, 2 servers - not clustered - 1.1GB of incoming mail per day after 3GB of rejected spam.