Some bits of software can "stretch" the video so that it shows at the right aspect ratio on the Xenarc/Lilliput screens, even when running them in resolutions such as 800x600 (which in my opinion is the best thing to run them in if you can't do 800x480)
If you want to know my reasoning behind that, do a
I'm not updated on the history of 800x480 on VIA Epia hardware but if the limitation is in the drivers then third-party software might be a solution. There is a company called SciTech (http://www.scitechsoft.com/) who develop graphic drivers for most chipsets on the market. I talked to them in another matter but asked them if they have drivers supporting 800x480 on WinXP for the Unichrome chipset used by Via. They said that they did not but if someone would send them hardware they would be happy to develop one. So if someone really wants to have 800x480 I guess they could contact SciTech to set this up.