You want Shader Model 3. If you can afford it, go for the 6800. If not, just get a eVGA 6600GT. You can upgrade to a 7800GT in a little while and I am not sure but does anyone know if eVGA has the step up program still, so he could trade in the 6600GT for a 7800GT and pay the difference?
DFI makes the best motherboards, MSI is good too. Never heard anything about Soltek.
Make sure you get a good PSU otherwise you could fry your components if the PSU goes out. Good brands are OCZ, Thermaltake and Antec.