When you first install Wondows XP, you have colour shemes, Silver, Oilv Green and the standard blue. Is it possible to change that colour, without downloading a theme?
Nope.
Luna (the name of the default XP theme) is ugly anyway. Look for a copy of windowblinds maybe (check the trading forum here =o) and find some themes for that. There's some really nice ones, and also actually a fair share of luna re-colours.