First, the web servers and mail servers etc. should go into the DMZ that you create. (just another interface). As far as addressing goes you can use either publics or privates in your DMZ, it doesn't matter. What does matter is rather or not you NAT. If you are using privates then you need to set up a NAT
global (outside) 1 206.60.60.60-206.60.60.254 [NAT Pool]
nat (inside) 1 10.1.1.0 255.255.255.0
Publics
static (dmz,outside) 206.60.60.0 206.60.60.0
nat (dmz) 0 0 0
The static make the 206.60.60.0 network visable on the outside, the NAT statment says don't NAT 206.60.60.0 in the DMZ.
I suggest you reaed up on this and look at as many examples as possible before you do anything to drastic.
MS