the guy at the local shop said he may have to reinstall windows,but would save all my data on the hard drive.
where do things like my photoshop brushes live?

under program files\adobe\photoshop.

or Program files\adobe\adobe photoshop, something similar and obvious like that. I don't have PS here at work to look at the exact name.

will they be safe from a reinstall of windows?

I don't know, it depends on how it's being done. If he intends to back up your data, format the drive, and install Windows fresh, then no, not safe. If he's just installing Windows over top of itself, then it should be fine. It's been a while but I believe you HAVE to back up your profile (c:\documents and settings\<username>) before reinstalling over top or it deletes the data there. So be sure that's backed up just in case. Everything else should be fine where it is, as long as he's not formatting the drive.

he hasnt even looked at the machine yet,hell let me know tomorrow . . .