Frustratingly none of the main VM software vendors (VMWare, Microsoft Virtual PC / Server and Sun VirtualBox) offer a way to resize a disk from the standard user interface. It is possible, but it takes a little fiddling to get it to work.
Stuart 'Stevie' Leitch's blog on Software Development, Java Technologies, Security and Testing
Don't Panic! blog and example code by Stuart 'Stevie' Leitch is licensed under a Creative Commons Attribution 3.0 Unported License.