Vista updating failed
Running defrag is advised considering that your computer is not new but my clients lately, especially on brand new OEM desktops.
I have used every Windows OS since windows 3.1 and I know for a fact there has never been a Windows OS prior to Windows Vista that was as reliable, and robust as Vista, I dont reboot my computer for weeks at a time, sometimes months and if it wasnt for updates requireing reboots, it would probably be even longer.
Dell finally agreed it was a motherboard issue but would not replace it free, stating the laptop was out of warranty, even though Dell had documented our MANY calls from the month we purchased the laptop.
Needless to say, Dell has lost THIS family business as customers.
I also suggest that you install the latest version of Firefox 4 and select add ons and install Bit Defender.
You will have a tiny Red dot in the Tab that let's you run it at will.