Not as much as I would like
I'm not personally knowledgable of Windows Live OneCare Backup and Restore, but if you are worried you might damage the contents of someone else's machine perhaps it may be best left alone.
You don't mention what operating system is on the computer or what types of files you wish to backup. Perhaps you didn't notice the "Note" in red above the text box in witch you typed your message, i.e.
Note: If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem. Also please exercise your best judgment when posting in the forums--revealing personal information such as your e-mail address, telephone number, and address is not recommended.
Personally I have found NTBACKUP to be somewhat unreliable as it will occasionally restore some files to incorrect locations and sometimes not at all.
Probably the best backup is maintained on removable media such as CD, DVD, external hard drive or flash drive. If you are only concerned with protecting some documents and programs or programs setup files, the fasted and least costly would be to copy them to a CD/R or CD/RW. And the leastly costly (really free) way to backup the entire system including settings is to create System Restore points. For just in case, a couple of SR points would be wise.
Another (or additional) option would be to create and use an indiviual Profile that way you won't even have to tamper with documents, etc. in your Mom's profile.
Hope something here is helpful.
Have any of you tried this service??? I am trying to work on my mom's laptop...it is slow...slow...slow....but as I not very knowledgeable...I need to make sure and backup here stuff in case!!! She is visiting so does not have her original Windows CD or I could just install their neat ntbackup program. Don't want to have to purchase something. Thank you in advance.