I hope you have Ad-Aware / Ad-Watch at least.
Try a Panda online anti-virus scan.
http://www.pandasoftware.com/products/activescan.htm
If it is a broswer hijack it helps to use Security Task Manager or WinPatrol.
You can find other anti-malware utilites at my eSnips page:
http://esnips.com/web/anjunasOtherStuff
Hijack This is highly recommended. A rollback (system restore) will not always cure such things as spyware, viruses, trojans, worms. You need to clean them from your system by using utilities and your own knowledge.
Try arranging your main Windows System folder(s) by date modified and see if you see anything suspicious there (a recently dated suspicious .exe file, for instance). There might also be things buried in Program Files and other places like shared application folders.
If you need more one on one help, I am willing. Helps if you have an instant messenger of sorts. I am on MSN (now Windows Live)
AIM and Yahoo. Much luck to you, I can even send you the best utilities that I use.
EDIT: You could also just try searching your System for the word "shoppingcamel" and see if it comes up with any file or prefetch by that name (Start > Search > Find Files and Folders). Sometimes you can catch 'em easy.
EDIT 2: Oh, and hit Ctrl+Alt+Dlt to see if anything odd is running in real time. Sometimes you can see the file name (again usually an odd .exe) and any possibly related files from there, too.
EDIT 3: As for paying for security, my advice is: Don't. I use AVG Free and a swarm of other utilities, plus my own brain and eyes and 10-yr experience (yes I remember when spyware didn't exist!) and I still catch some that pass by all my usual (regularly updated) defense utilities.
EDIT 4: Sorry this is so long. If something persists beyond all this, it may be so naughty as to be in your startup (msconfig), too. You can go to Start > Run > (type the word) msconfig > Startup (tab) and see if there are things there that shouldn't be. That is not the only place things can be buried, but common shopping spyware shouldn't be too much trouble, honestly.
Again, PM (or IM or e-mail) me if you need more help. I am more than glad to assist with such troublesome things. Ever since I got and rid myself of the recently infamous TheMatrixHasYou time bomb explosion, I can empathize, sympathize, and be glad to assist.
Here's a
help page for such. Apparently the advice worked for this person, so I think you should be all clean soon.
I searched an exact term for shoppingcamel at Metacrawler.com and it comes up with a lot of additional instances. Looks like it is something very common, and most likely an updated Ad-Aware/Ad-Watch would catch. Avant Browser (and Orca Browser) also blocks such common spyware URLs by default. But it doesn't support the Neopets toolbar. (Awwwww.)