Help needed on setting up VPN and Remote Desktop

[iamjon]

I am not a techie, I have basic knowledge in setting up networks etc.
I have a Netgear DG824M ADSL Modem/router/hub with two Dell optiplex's and a Inspiron notebook all talking (sort of) fine, sharing the internet connection etc. None are set as a server, all are running XP pro.
At home I have 1 PC running xp pro, ADSL.
I have static IP's at both the office and at home.
To cut a long story short - why can't I get my home PC to access the work PC by VPN and use the remote desktop?
I have followed pretty much every possible tip and note I found and I'm starting to tear my hair out!!

Is it something to do with the firewall/routing and the IP's within the network at my office???

Anyhelp greatly appreciated!

Thanks,

JOn