Performance and Internet issues

All of a sudden my Dell laptop (just over a year old, go figure) has started acting funny. Here's some of the issues that started happening all of a sudden

-It runs super slow at times and freezing up, svchost.exe seems to be taking a lot of resources up when that's happening
-The memory card reader doesn't work. It makes the noise that a new device has been recognized when I put one it, but it never shows up in My Computer. The memory card reader does appear to be working properly in device manager.
-Both firefox and IE aren't loading some sites. I'm connected to the internet and some sites load just fine and others never seem to load- and it's not that the site is down. The list of sites I can't access I'm starting to discover is big, and which sites can be access and which ones can't doesn't seem to follow any pattern- I can access google & gmail, but it won't perform a search (either from the page or from the search toolbar in both IE and firefox). I can access and log into my banking sites, ebay, and other random sites (some secure, some not). But I can't access weather.com, the Neosmart forums, the Dell community forums, dell.com, and others. I can access facebook.com, but I can't log on.

My first thought was I have some type of spyware even though I'm very good about not downloading stuff so I ran a ad-aware scan and it came up with nothing. I also ran a hijackthis scan and everything was normal there too.

I'd been noticing recently that some windows processes in task manager are using what seemed like a large amount of memory. I then looked my other computer and on the problem one Explorer.exe is running around 99,000 - 120,000 kb- on my other computer it only runs around 14,000-35,000, that big of a difference between the two machines (both running xp- the problem one pro on a laptop, the other home on a desktop) is not normal.

I've already Defraged my drive (even though the analyzer said it wasn't necessary) and ran Ccleaner and fixed a whole ton of things found. It doesn't seem to have fixed the issue of the progresses running on more memory than usual or the internet issue.

I ran Process Explorer also and can save and send a log file/screen shot if need be. There's a lot of stuff highlighted in pink- all under services.exe and lsas.exe. Under services, the svchost.exe process (dcom server process launcher) has a couple of McAffee processes highlighted in blue and wmiprvse.exe is in dark orange/brown.
Explorer.exe and all processes under it are highlighted in blue- under it would be the programs I have running (firefox, google talk, dell utilities, and two rundll32.exe "Run DLL as an App" processes.

This morning I was comparing task manager processes on the two and the laptop started freezing on me. Svchost was going way up (made it up to like 120,000 kb) and then the computer started freezing. I had to leave for work and didn't have time to open up Process explorer or anything to get a more detailed report. At the time I was running McAffee (it was scanning for viruses), Windows Defender, Word, and I'd just launched Firefox, but it hadn't loaded yet. Like I said, I couldn't get to see what specific service svchost was using, but I'm guessing it was probably dcom service process launcher since that was the one highlighted in Process Explorer yesterday.
I realize that McAffee is a resource-intesive program, especially when scanning, but in the past this may have slowed things down a little, but today it was to the point where it wasn't responding to mouse/keyboard clicks. When I get home today I guess I'll find out what happens I leave the computer be for a bit, if it finishes whatever it was doing and fixes itself, or if it's still frozen/acting super slow. The other day it froze up and it took me 10 mins just to shut it down (every click of the mouse/keystroke took about a minute to be recognized)

Any thoughts on what's causing any of these issues or how I can fix them?