cannot upgrade from vista to windows 7 ...help please

[sandro]

The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue.


There is not enough free space on partition (C. A total of 12853 megabytes (MB) of free disk space is required. Try Disk Cleanup, or moving files to an external location such as a CD, DVD, or external hard drive, and then restart the installation.

You can fix this problem with our resize disk functionality (just in case of USING VIRTUAL HDD - please pay attention). Shutdown Windows guest OS. Make backup of VM (you can use Clone functionality for this). Then go to configuration editor, select virtual hard disk at Hardware list, type Resize and follow with wizard actions.

Upgrading Windows will affect the following devices and/or programs:
These devices might not work properly after the upgrade. Before upgrading, we recommend updating the drivers for these devices. Cancel the upgrade, open Control Panel and search for "update device drivers", or go to the device manufacturer's website to search for updated drivers.
Sound, video and game controllers: Intel(r) 82801BA/BAM AC'97 Audio Controller

I guess it's just warning. In any case this problem exactly related to Windows and i think Microsoft support has to consult on it if you will have problems.