You can't resize the boot partition on the fly as it were, but you can use other apps or even do it from another PC if you take the hard drive out.
You got another vista/7 machine handy where you can plug this drive in? IF you have the right click computer, manage, disk management, delete what was know as E: on the laptop, right click what was her C: and choose Expand.
Otherwise you can do it with other other tools, but Vista/7 has this capability built in, just not for boot partitions because they're generally in use.
A free tool would be the Vista/7 install DVD, choose to repair computer then open a command prompt and use disk part.
http://support.microsoft.com/kb/300415it would be something like:
diskpart
list partition
select partition 1 (1 being representative of the number that corrosponds to her C:)
extend
exit
then reboot and you should then see that what was her C: is now taking up the entire capacity of the hard drive, pop the drive back in the laptop (this method can also be done from her laptop as Windows isn't loaded, thus stopping the boot partition from being altered)
I'm sure there are tools out there, but that's what I'd do
PS: backup before trying this with ANY tool/method.