The first step is to make copies of any important files that you have. If you have the luxury of two computers you can keep copies on both to reduce the likelihood of losing them. If you don't, then you can use a usb flashdrive or usb hard drive as a storage medium. It really depends on the size of the files and the availability of cash in your purse/pocket.
The more important the files the more copies to have so, assuming that the computer has the capability, burning the files to a disk as well and keeping them in a separate location is a good idea. Although it sounds depressing to point it out, if your house was to catch fire you would lose both the computer(s) and the disks if you kept them together.
It's really a percentage play, the more copies you have, the less likely you are to be unable to access them in the future. One copy could become corrupted, a second could be lost, a third... Decide how bad you would feel if you lost the files, in this case pictures, and make sure that you have a back-up system that lets you sleep soundly at night.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the event of an infection there are a number of PC forums where you can receive help - such as this one, funnily enough.
All you would need to do is to follow the instructions here
and somebody would be along to help as soon as they could. There is no guarantee however that the PC could be cleaned and it may be necessary to reinstall the operating system, as it sounds like you have already done, so backing up files is vitally important to ensure that they aren't lost.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the mean time you need to have an active firewall, which you may have built into Windows depending on which version you have, and a resident anti-virus program as a basic level of protection. There are various options, some paid-for and some free, depending on your preference. Do you need links or have you got this level of protection set up already?