Mr Draper
You have experienced what a lot of people do when they install new software, it's a bit like this...
"Hmm I'm Photoshop and am much better than any other program on this machine to open those type of files so from now on when you want to open those type of files I will do it for you."
Now what typically happens is that you try the new program and it is crap (any free software thrown in with printers and scanners IMHO) or it is a little baffling and we decide we no longer want to use it and free up the disk space it stole. Unfortunately when we remove these programs (again IMHO) it never ever puts your system back to the way it was. (exeng is totally correct XP helps rid you of these problems as long as you create a system restore point before installing, then if you don't like it - bye bye.
Do you remember what program you used to use to open jpg's etc. I am guessing it may have been Internet Explorer if so find one of your pics hold down one of your shift keys and with your finger on the button right click on the file and choose open with, you should be presented with the choose program to open file window where you can choose what program you want to open it with, there should also be an option to always open the file with this program if you tick the box that should solve your problem.