Cisco PixFirewall and McAfee Webshield e500

[dapCZ]

Hi all,

i have 2 devices : Cisco Pix Firewall 520, 4 interfaces and
McAfee Webshield e500, 2 interfaces. How can i connect webshield to our schema for best performance and best filtering options and which operating mode select <explicit proxy mode, transparent router mode,transparent bridge mode> ?

Network : |
OUTSIDE interface
office1-----| | |--mail
| | |--ns
office2-----| | |--ws
---VPN interface<PIX>DMZ interface--|--....
office3-----| | |--....
| |
office4-----| |
......------| |
......------| |
......------| |
INSIDE interface
|
|
|----|---|----------|---|---|
| | | | | CLIENTS
| | | | CLIENTS
| | SERVER-2 CLIENTS
| |
| SERVER-1<Exchange in future>
PROXY


Server mail on DMZ is only SMTP in future (now pop3,smtp).