There certainly will be some new products for PCs between now and January, but nothing too critical for desktops. Like already mentioned, Intel's new Quad processors will debut and NVIDIA's DirectX10 video cards will become available too. However the only models of Quad expected to be out by January is the QX6700 and possibly the Q6600. Chances are you won't want (nor need) to spend $1,000 on a quad-core processor when all you're doing is word processing and surfing the internet. Also the only DX10 cards expected to be out by January are the NVIDIA 8800GTX and the 8800GTS (~$1,000, ~$750 respectively). They're both high-end enthusiast/gaming video cards.. you won't need that. Plus as long as you buy a PC with a free PCI-x16 slot, you can always upgrade to a DX10 discrete card solution later on.
The main improvements will be in the notebooks market. Intel is scheduled to release their 4th generation Centrino platform for laptops in Q1 (probably not Jan, but close), in which it's features are very much geared towards Vista performance.