Current configuration:
BM 3.5 SP3 with 2 NICS, NW 5.1 SP7
We have the public subnet 200.x.y.0/27
LAN 10.6.0.0/16

NIC #1(Private) bind 10.6.2.2
NIC #2(Public) bind 200.x.y.2, dynamic & static NAT (200.x.y.3 ->10.6.2.3)
Default route: 200.x.y.1 (Cisco Router)

HTTP proxy and VPN services(site-to-site, client-to-site) flow thru public
interface GREAT! No Problem, but....
we have a DSL connection, so we want HTTP Proxy to flow all traffic over
this connection and VPN services stay over dedicated link.

This is what I did in a test configuration:
NO changes to NIC #1
NO changes to NIC #2
Add one NIC to BM
NIC #3 (Public) bind 192.168.1.5, dynamic & static NAT (200.x.y.2 ->
200.x.y.2)
3com DSL router bind 192.168.1.1 to do PPPoE
Change default route to 192.168.1.1

Result:
HTTP traffic flows thru DSL without problem, but I can not ping public
address 200.x.y.2(NIC #2) so VPN is down. I did a trace but it stops just
one hop before my public address. I did ping & tracert from a PC connected
to internet via dial-up.
If I returned default route to 200.x.y.1 everything works fine but HTTP
traffic goes thru dedicated link(200.x.y.2)

Disable NAT on NIC #2 but I got same result.
Just dynamic NAT on NIC #3 but I got same result.

Can I do this? or am I just dreaming?