I am connecting to a VPN through my home computer but when I am connected to the VPN I can no longer access the internet on my personal PC. I need to then remote desktop into my PC at work to get internet access and this is really annoying. This there anyway I can "block" the internet access being provided by the VPN connection?
It is possible if you have a working knowledge of the route command in your OS. You can effectively tell your PC to only route traffic to the VPN network over the VPN connection, and send everything else over your normal connection.
It's hacky, but it can get the job done. The batch file I use is on my home PC so I can't give a sample right now. Hopefully someone who knows the commands off hand will be able to give you more info.
VPN clients (like the "VPN Network" in Windows) often have an option whether or not to redirect all traffic over the VPN connection. The remote VPN server may or may not actually allow such traffic.
Note that OS X has a different default than Windows. Windows by default sends all traffic over VPN, but a Mac does not. (On a Mac, the Advanced button shows an option "Send all traffic over VPN connection". Windows has a similar option; in Windows XP it was called "Use default gateway on remote network", which would show by opening the properties of your VPN network, selecting tabsheet "Networking", selecting "Internet Protocol (TCP/IP)" and clicking "Properties", and finally clicking "Advanced"...)
When all traffic is sent through the VPN, then even "normal" web browsing is done through the remote VPN server. This might be useful when traveling in some countries that filter certain web sites. As the VPN connection is encrypted, using it for all traffic might also be more secure when not knowing who can listen in to the network (hotel, internet café, Starbucks WiFi, ...) that is used to connect to the internet. And sending all traffic over the VPN might be a bit more secure as any "hacker" (or spyware) who has gained access to the workstation will be disconnected as soon as the VPN connection is started. It depends on the security of the VPN server whether or not such unwanted traffic could be re-established through the VPN server.
It also depends on the policies of your company whether or not this option should be changed.
This will depend on the VPN client. From memory the Cisco VPN allows you to specify that only traffic for a certain IP range will use the VPN connection, however this is also controlled by the profile and the security on the company side. Some companies disable this feature as it is potentially a security risk.
If you are using the Cisco VPN you can try and use the workaround mentioned here.
Windows 7 comes with the Agile VPN Client. Apart from manually hacking the route as already mentioned I can't find anything that you can set to allow this otherwise. There is a detailed article here on how it works and it may contain the answer.
I worked around this very annoying problem by running the VPN client and remote desktop software in a virtual machine. Basically, I created a dedicated Windows XP VM for work/VPN/remote-desktop use. My host operating system, Windows 7, is still able to connect to the Internet and other devices on my network, including my network-based printer.
I use VMWare, but I imagine Virtual PC could do the job. The trick will be making sure your VPN client software is compatible with the VM you choose. I had zero problems running the Cisco VPN client in a Windows XP virtual machine running under VMWare Workstation.