When email is downloaded by Microsoft Outlook (external link)
it is stored locally in a special file format with the extension PST, the default location of your PST file varies by which version of Microsoft Windows you have installed.
For Windows 2000/XP (external link)
the default location is:
C:\Documents and Settings\<user_id>\Local Settings\Application Data\Microsoft\Outlook
For Windows Vista (external link)
the default location is:
C:\Users\<user_id>\AppData\Local\Microsoft\Outlook
This is because Microsoft changed the LOCALAPPDATA location when they created Vista, yours can be found by opening a Command Prompt window (Run > cmd.exe) and then running set.exe, this will display a list of special strings that have been setup for your current login. If you search through them you should find the LOCALAPPDATA string, this is then used to build the default location by adding MicrosoftOutlook onto the end.
on the PC again after a long break and I started getting graphical corruption such as in the picture below, floors and walls were disappearing completely, it was like a wall hack had been enabled. Checking online I found out the it is a conflict with 
on the PC:
under Steam will still not load correctly when using Vista, in order to get it to function correctly you will need to import the following keys into the registry, both of these fixes assume you have used the default installation path for Steam: