I am planning on moving my GF4 4400 and current Maxtor 80g HD over and will upgrade my Video card later when the next gen of Nvidias come out.
You may want to be careful with that plan. If I interpret it correctly, you mean that you plan to buy the latest and greatest nVidia offering once it is made available. Either that or you are anticipating a price drop in current cards once the next line arrives.
The first is not necessarily a good idea, as it has not been determined if the NV40 series will be both PCI-Express and AGP [although this is likely] or just PCI -Express. You will be SOL if it's the latter.
The second is a good idea, as lower price for a good part is a good thing.
The shuttles have overclocking options, but aren't too friendly in that department, as the extremely small space hinders airflow.