I've been using XP mode on Windows 7 for a while and it has been proving useful to have an old XP copy available for things like compatibility testing. One issue I had is that it comes configured with only 256MB of RAM available to the virtual machine which tends to make it limp along somewhat with the hard drive thrashing away as XP tries to shuffle stuff into and out of the swap space.
I had plenty of RAM available on the host machine but it wasn't immediately obvious to me how you could increase the amount of RAM available to XP. Here's how I did it, if anyone has an easier way please let me know.
Step 1: Start up the XP Mode Virtual Machine. One way of doing this is to type "XP Mode" into the Windows 7 search box when you press the Windows pearl at the bottom left
Step 2: Once the virtual machine has started up, select "Tools" then "Settings". You'll notice that the memory size is set to 256MB but you can't change it because the virtual machine is running.
Step 3: Click on the "close" option and select the "prompt for action" radio button to allow you to opt how you want to close the virtual machine. If you don't do this it will always hibernate when you close it which isn't what we want - you still can't edit the RAM value when the virtual machine is hibernated.
Step 4: Click OK on this screen, then - and this is important - choose "File" and "settings" again and leave the dialog box open.
Step 5: Choose "Action" then "Close", and choose "Shut Down" from the drop down box. Remember you must still have the settings dialog box open at this stage.
Step 6: Once the virtual machine has shut down, you will now be able to edit the RAM value in the settings Window that you left open.
Step 7: Once you've selected the value you want, click Ok then start up the virtual machine again.
With 1GB of RAM it runs a whole lot faster and smoother that's for sure.