I have 1and1 as well with home Exchange in vmware.
under the 1and1 settings for your domain (ie: riciscool.com) you have to change the mx records form '1and1 servers' to the internet address of your home computer connection, which is probably not a static IP, right?
You should go to DynDNS.com and register a free web url (riciscool.home.net) and then DynDNS has a client that you run on your exchange server/DC at home, that updates the dyndns url with your IP at home, each time it changes.
so riciscool.home.net when typed in will go to your home IP, anytime.
in the 1and1 mx settings, you can change your MX record for riciscool.com to point to riciscool.home.net.
while your in there, make a subdomain for riciscool.com , called email.riciscool.com and point it to riciscool.home.net
so anyplace you can type in email.riciscool.com and get to your home connection.
your home domain can be anything at all, ric.local, ric.home, ric.me, whatever you like.
after you get the domain controller setup, then you install exchange (petri.co.il has alot of helpful tips), after exchange is installed (dont forget sp2 for it) you then go into the system manager and right click on the item on the top of the list (forget the name right now) and there should be an option to configure internet email, this is where you enter the web address you want to do email for, riciscool.com
One problem you may run into is emails getting returned to you or being undeliverable, due to some email systems not accepting emails form home based IP connections, this would need to route your outgoing exchange emails through your ISP's email servers, not too hard to configure.
dont forget to forward port 25 to your internal IP of the exchange server, as well as port 80 and port 443 (you might not need port 80 down the road, but testing with it will help)
And hopefully your ISP doesnt block port 25.
PM me and I can give you some pointers if you get stuck< I think I have screen shots of the MX records with 1and1 that I setup as well.