I have been using TeamViewer for this for some years. It works quite well, is localized so less computer literate parents outside US/UK have a chance of running it, and is free for personal use (even on weekdays :-P).
Windows Vista, 7 and 8 come with "Remote assistance" which I find to be quite useful, get your mum to run it and (the gods willing) you will be able to access her desktop via it, without the need for extra software. I use it to fix my dads computer often.
You could try an old trick that I used during my tech support days.
You can kill Windows explorer with task manager and then use the File/New Task option to restart explorer with a higher level user. You can then do whatever you need to as that user (e.g. control panel, delete files, add hardware, etc). When you're done, you can just repeat the process and start explorer again as the original users.
I haven't tested 100% in Windows 8 (killing and starting explorer as another user does work), but it should work in Windows 7 and below.
I used this any time right clicking an exe and selecting "run as" wasn't enough
TeamViewer is great for support like that. It's pretty easy to get even non-technical people to start it up and then they just read you a simple code and you can connect.