Whilst I can connect to the office network using the Junos Pulse iPad client (to a backend Juniper SA2500 SSL VPN) I wonder if anyone has managed to setup a Windows server 2003 VPN using PPTP?

I tried this already and whilst I managed to get a connection, I could not see anything on the actual LAN.

So, you are connecting via VPN to an Enterprise Network with an IPAD. But, here is the issue. Since almost 80% of Enterprise Networks are built to use Microsoft platforms, the usage from the Apple platform is still in that 20%.
Your best and kind of only bet is to use RDP (Remote Desktop) or some equal version of RDP. You will be basically driving your network connected, Microsoft platform PC.

Hope this helps.

Thanks for the response.

I managed to set it up using L2TP over IPSEC with a Pre shared secret for added protection.

In terms of Enterprise connectivity, I did it for email (our Exchange server is LAN based only), RDP, Citrix and SMB file transfer. With Microsoft's grip, it will always be a compromise untill Windows 8 tablets appear.