OK, sorry about my earlier comment. I read your first post wrong
The first thing to check is that your router will handle a WAN multi-IP subnet. Many will not. I do not know the Dlink routers but this extract from the link you posted, does not look optimistic:
"
With Virtual Server Mapping, the router can be set to allow separate FTP, Web, and multiple games to share the same Internet-visible IP address while still protecting your servers......
Note the use of the word
address - singular.
------------------
Assuming that the router will handle a multi-IP subnet, you can still run a web-server using port forwarding - just forward port 80 from the IP address you chose from the available five. The router will keep all other ports secure.
------------------
If you really want the local machine to have a WAN IP address (with all of its ports avavailable from the Internet

, then you need to disable NAT for the address you want to use - Again, not all routers will allow you to do this, even though they will allow port forwarding from selected IP addresses.
------------------
One router which will do it all is the Dray
Tek 2800 series (or an old 2600 series, if you can get hold of one). You may find the Dray
Tek help files on the Zen knowledgebase useful for early reading:
http://www.zensupport.co.uk/knowledgebase/default.aspx?cNode=2Q2K0S&pNodes=8L8F3J:6A8N2N
ZeN Home 500 - DrayTek Vigor 2600VG
Acorn RiscPC700 (RiscOS 3.5) - Acorn A410 (RiscOS 3.1) - Sun Ultra 10 (Solaris 7)