Certain to have a new mother load of security flaws which will alloe our PC's to get infected. Isn't Longhorn 64 bit as well?
I don't think the article mentioned whether it was 32 or 64 bits, or even if it was backward compatible. Several posters mentioned that it was both, but the question of backward compatibility was asked but not yet answered.
As to security flaws, well as a general rule, the more complex a system gets, the higher will be the failure rate, even without deliberate intervention from the global anarchistas trying to inflict as much damage as possible...and as often.
The only thing I can suggest is keep your anti-viral signatures, fire walls, and trojan guarders up to date, especially if using a fast connection which is prone to be on-line more often than dial-up.