Tri,
Hate to bring this up but McAfee is a known resource hog and can and will slow down your system. Your problem started prior to installing that on your system, so its probably not the cause. Just FYI on how it can be a resource hog. There are plenty of AV programs out there that work just as well for free like Avast or even the Windows Security Essentials.
What did you install/uninstall before this slow down happened?
What was your previous AV (anti-virus) software and did you uninstall it all prior to installing McAfee?
Definitely hit Crucial and their Crucial Scanner and find out about adding more RAM. Once you know what to look for, type, style, etc., you can call around and get a better price or price match without having to pay for shipping.
You can uninstall programs by going to the MS globe (bottom left on Windows 7) that replaced the green Start button, selecting Control Panel then selecting Programs. That should help you uninstall Skype. Then run CCleaner to remove the residual debris left over from that.
CCleaner will remove registry listings for old programs that have been uninstalled and clear up some space on the HDD (Hard Drive). Don't expect massive free space to appear though. Another free utility program besides CCleaner and both CCleaner and this one are recommended by PC techs, is Glary Utilities. Glary is free and easy to use. Really easy. Just let it do its thing and stay with the default settings. I've installed Glary for senior citizens that have limited knowledge of PC's and they love it because its easy to use. And its free. I have both Glary Utilities and CCleaner on my system and use them both.
http://www.glarysoft.com/
Be careful going back to a restore point. Make sure you back up with USB sticks/CD/DVDs so you save data prior to hitting that restore point. Strange things can happen so back up as much as you can.
You stated you were running Win 7, 32 bit edition. Unlike earlier operating systems, Windows 7, both 32 and 64 bit, use more RAM then XP and Vista. The lack of RAM could be the total crux of the issue. This sucks as you're going to be 'removing and replacing' to find the problem.
How familiar are you with your computer? Do you know if you're running a single core or dual core processor? Single core processors with limited RAM and a higher operating system (OS) like Win 7, can bog down when something new is added like a program.
If you feel confident enough, try downloading CPU-Z or HW Monitor. Both are free and both will tell you about your system. One, CPU-Z tells you what hardware you have, that would be HDD, CD/DVD optical drive, any sound cards or video cards you may have installed and about your RAM. HWMonitor shows temps (that can be an issue too, dust buildup inside a PC can kill it), voltage (that will show you if your power supply is going out), and fan monitoring to let you know if your fans are operating like they should.
http://www.cpuid.com/
Check your hard drive to see if it needs defragged. Also check if you have the option to install another HDD, larger or smaller, to act as backup instead of a partition on your existing hard drive. Hard Drives are also relatively inexpensive and you could get a 500gb or 1TB HDD pretty cheap. No need to partition something that size.
Getting to the add-ons and search windows issue. You stated you use Firefox. Along the upper left you should have File, Edit. View, History, Bookmarks, Tools, Help. Click on Tools and select Add-ons. That should open up a window that shows what add-ons you have currently installed on Firefox. That should also show you what add-ons are not compatible. Personally, I'd remove AdBlock and install AdBlock Edge. Its a smaller program for Firefox and it works a lot better than the original AdBlock. You can find it by searching for it in the add-on section of Firefox.
With Firefox there are tabs just below the File, Edit, View, area. Below those tabs are the search windows.
The search windows are just below the whole File, Edit, View area. That is the white horizontal rectangle that web addresses appear in. To the right of the rectangle will be another smaller rectangle. If you have more than those 2, you need to remove them. Those can normally be found in the Start (MS Globe, bottom left that replaced the green start button), Control Panel, Programs, uninstall a program.