Hi Cheeky,
Assuming you're on Win XP, to increase virtual memory goto control panel choose System then the Advanced tab. In the performance box click on setings then Advanced tab, Virtual memory box is at the bottom, click on change to see how much you've got set.
3Mb doesn't sound like very much memory, it could be that you have some progams running in the background that are causing the install to hang. You can check what is running by opening Windows task manager (CTRL + ALT + DEL)