MS Proxy 2.0 is enough ?

["Ferran Rebollar Cervello" <ferran.rebollar () sema es>]

Hi all,
for security reasons we have two isolate LANs: LAN_A and LAN_B. 
But now, LAN_A users must access an intranet web server in LAN_B and LAN_B users must acces the corporative mail server 
in LAN_A. 
Other traffic/services between LAN_A and LAN_B will not be allowed.
Using MS Proxy 2.0 is enough ? Better a strong firewall (like Checkpoint's Firewall-1) ?
thanks in advance,
Ferran