Given desktop and laptop prices today, and the new Vista utilities for migrating apps and files, buying a new PC is going to be the sensible option for most people.
The easiest way to get Vista is to buy a new PC after Jan. 30. If you want a new PC sooner, make sure the hardware is Vista-ready and see if the vendor is offering a coupon for a free or low-cost upgrade when Vista comes out. It is essential to compare the cost of buying a new system against purchasing Vista and upgrading your current PC. By the time you add up the cost of Vista plus any required hardware, it might be make more sense to get a new machine.
On a related note -- a WSJ article yesterday ("When iPods Die"; subscription required) suggesting most people consider media players and phones disposable after a year or two. Excerpt:
As pricey as many models of the iPods are, some users seem to accept the idea that their iPods are more or less disposable, a phenomenon common in the cellphone market where users regularly upgrade to more stylish models. One gauge of that, Mr. Arter says, is the growing popularity of a buyback option iPodResQ.com offers for iPods with technical problems. Rather than pay to have the devices repaired, growing numbers of its customers opt to sell them for parts to iPodResQ, typically for between $35 and $95 -- money that can then be applied to the purchase of a new iPod.