I haven't been checking this group all that often lately so if you reply and don't hear back, well what can I say, you get what you pay for.
Problem one. Your router config. Your outside address should be on a separate subnet then your inside. The 5 IPs you mention don't fit into a subnet, there should be more or less then 5.
You can use any private subnet between the router and pix just make sure the default gateway on the pix is the IP on the inside of the router, that there is a route in the router for your public subnet pointing to the IP on the "outside" of the pix, and that the NAT on the pix is using your public subnet. This all comes back to your subnet problem.
A typical system would look like this (I'm making up all the IP addresses).
DSL interface on the router has an address of 18.104.22.168 with a mask of255.255.255.252 (the router at the other end of the T1 would be 22.214.171.124)
You can set the router's default gateway as either the DSL interface or126.96.36.199 I like to use the far end address but that's just me. The router already knows that this subnet is on the DSL interface since it is directly connected.
Assume that your public subnet is 188.8.131.52/29 or 184.108.40.206 through220.127.116.11 The 0 and 8 are your network and broadcast addresses and you can't use them, this leave you with 6 usable IPs.
Set you router ethernet port with an IP of 10.10.10.1 255.255.255.252
Put a static route in the router so that 18.104.22.168/29 goes to 10.10.10.2 (the "outside" address of the PIX).
The PIX will have an; outside 10.10.10.2 255.255.255.252 inside 192.168.1.1 255.255.255.0 default gateway 10.10.10.1
You can now use your entire public subnet for NAT/PAT within the PIX.
The config gets a little easier if you don't mind using a public IP on the router ethernet and the PIX outside. In this case the router ethernet would be 22.214.171.124 255.255.255.248 and you don't need a static route in the router since the subnet is now directly connected. The PIX would be; outside 126.96.36.199 255.255.255.248 inside 192.168.1.1 255.255.255.0 default gateway 188.8.131.52
Thus concluding today's class of IP 101.