Hi. I would like to talk about Vista this time.
The newest operating system and I think it has much promise. The 64 bit version should be very secure, although it still has ways to be taken over. Listen to episode #66 at http://www.grc.com/SecurityNow.htm for an in depth discussion about vista security.
I purchased a Toshiba laptop with Vista and at first there were several problems have mostly to do with drivers. Along the way I have noted more stability after some OS updates and Toshiba BIOS updates. I would recommend that you buy a new computer with Vista rather than upgrade. As with windows 95, there are hardware issue when upgrading old hardware to Vista.
Here are some basic tips about hardware I found out when buying my laptop.
You need at least 2GB of ram. While the minimum is stated at 1GB, Vista is a memory hog of the first order. I think 2GB is minimum and 4GB is best.
Get the fastest processor you can afford. It should be a core 2 duo of at least 1.6GHZ
You might also get a 2GB flash drive to use as a ready boost drive. This provides a place for the system to swap memory out to that is faster than a standard hard drive thus speeding up most applications and allowing more programs to open at one time.