Question : Private ipv4 scheme

I am planing on using the following ip scheme for a new Windows 2003 domain:

172.20.10.1-29      
Static network devices (Switches, routers and access points)

172.20.10.30-49      
DHCP reserved IP's (Printers, scanners, fax etc..)

172.20.10.50-99      
Static IP's for servers

172.20.10.100-199      
DHCP scope for clients

172.20.10.200-254      
future use

The network is a smallish network (50 users max) w/ your typical network devices (i.e. printers, file servers, ect..). This network will have an internet facing web server and an Exchange 2007 server.

Thoughts? Recommendations?  

Answer : Private ipv4 scheme

Seems very close to my set up here...  works well for me, however I have Exchange in my DMZ and private network for easy access from inside and outside... Where did you plan to stick your Exchange server?