I believe I mentioned here about my problems with anti-virus programs (stop updating) and concerns with having a virus. I can't find the thread, so I started this new one.
I downloaded Windows Security Essentials from the Microsoft download site onto my 5 year old Windows XP desktop, and thereafter my computer slowed way down. Seems I recall someone here recommending Essentials, but they noted it takes up a lot of system resources. I surmised this might have been the cause of my desktop slowing down -- has a Celeron-equivalent processor and less that 1 gig of RAM.
A couple of weeks ago, I saw a good price on a laptop and decided to buy it. Really nice . . . 17" screen, dual core processor, 3 gigs of RAM, 320 gig hard drive (I'm typing this on it right now). I decided to try Security Essentials instead of keeping the short (60-90 days) trial versions of Norton and McAfee. This laptop has not slowed at all -- loads very fast. So, maybe that was the problem with the old computer . . . insufficient resources.
I still plan to keep the XP computer, mostly because I had bought a 22" monitor for it a few weeks ago. Also, I have some peripheral equipment that won't work with Windows 7.
Just thought I would mention this, in case anyone might be interested.
I tried Windows Security Essentials last year on my Vista computer and it crashed it every time. Pretty weird since it's a MS program! Right now I'm using Panda with Win7. Panda is different that other virus programs because the database is kept on at their server so your computer only has a small client program. This is suppose to reduce the resource load on your computer and keep the database more up to date. I don't know how well it works but I haven't had any virus problems since I began using it.
Any computer will slow down in time because the registry and harddrive just gets filled up with a lot of crap- fragments of old files and programs. So the best thing you can do is save your data files to another drive and reformat and reload the OS every year or two. It's like cleaning out the cobwebs.