John has nailed a lot of the problems that I have seen in over 15 years of building/repairing and of course reformatting/recovering data/removing viruses/trojans/malware etc form folks who did not listen to what I told them.
Like John, I used to run Norton Systemworks as it was the premiere
suite available for all OS's. However back in oh say 2003 Symantec changed how Systemworks was structured and added a lot of GUI's to the system which substantially increased the size of the program to a point where systems that normally could handle Norton no longer were viable platforms. Norton is still a HUGE resource hog -- all you have to do is bring up Task Manager to see how much of the system resources Norton uses. The two largest resource hogs have to be Windows OS and then right behind it - Norton.
I remember when Bill Gates said 10 meg hard drive 640 kbs or RAM was all anyone ever needed. Now puters with less than 2 or 3 gigs of RAM are unable to adequately operate. So other Anti-virus suites are needed and there are some good ones out there.
My preference is for Iolo's System Mechanic Pro -- for a number of reasons. The A-V component is pretty intuitive, great updates and it catches pretty much everything that is out there. I have not had a serious virus attack in probably 6 years now. What makes Iolo better than Norton is the System Mechanic side of the suite which offers a complete toolkit to manage your computer including Memory Mechanic which actually will restore ram which has been allocated, utilized and then released back into the pool. No other program aside from RAMBooster does this. RAMBooster is not supported in the newer OS's although I still use it on my Wn98SE puter.
Esset is another good as is Kaspersky. As a side note, Kaspersky was up until about 3 years ago an integral part of Iolo's product line although it was a temporary collaboration as both companies were building up their own suites.
A must have just for insurance is to have some dedicated Anti-Malware programs. The ones I recommend now (Ad-Aware is off the list because of conflicts with a number of major A-V suites) are Malwarebytes
and most importantly,SpyBot Search & Destroy
. Sometimes they don't pick it all up, but between the A-V suite and these dedicated anti-malware programs it is pretty good protection.
However, like our Cub -- computers need maintenance. If you don't run the programs, they don't do their jobs/do them effectively. We make it a rule here in the house to run all of our A-V/Malware tools at least once per week.
As for laptops, I/we have owned a number of them over the years -- from 286's to the latest laptops on the market from Dell, Toshiba. IBM/Lenovo and Acer. By far and away the best on the market has got to be Toshiba. Also, Toshiba offers as an option in their warranty coverage for accidental damage. AFAIK no other company does this. The Toshiba is one of the best laptops on the market and the addition of this warranty makes it a no-brainer for me. Don't ask why I know this stuff. btw, probably the best laptop on the market has to be a Panasonic Tough Book - but with a starting price in the 3 grand area -- pretty much way too rich for most budgets.
I am currently running a Toshiba Satellite P-300 with about 3 gigs of ram and Vista as the OS. I prefer XP Pro but Vista is beginning to grow on me -- and I assume I will upgrade to Windows 7 at some point.
of course all of this is JIMHO.