Hi,
If you have enabled split tunneling, then the Internet would not work through the VPN.
Moreover, Internet ass such can ot work through VPN, even if you disable split tunnel, because PIX 6.x code is not able to redirect the traffic on any of its interface. The capapbility was introduced in PIX 7.X code. PIX 506 ca not be upgraded to 7.X code.
The only two options you have right now are:
1: Either enable split tunneling, that way Internet traffic will go out unencrypted.
2: Or you can put a proxy server in inside subnet of PIX, and point the VPN client's browser to that proxy server ip address. This would however work for http traffic only.
*Please rate if helped.
-Kanishka