Superb one easy to install & does not slow the PC.
Vista Rainbar is a application and easy for using. This sidebar, whose you can change the background between around ten choice, offers many gadgets such as clock, calendar, RSS feeds, weather... with the possibility, for most of them, to customize settings and skins...
the program is easy to install. It takes very little ram therefore does not slow down your computer, and of course, it runs on Windows XP but also as fediaFedia said "Works on Vista 100%" !
Attention, for installing it, follow the pdf file "Read-me" which is provided with the download, you will discover how the different gadgets function, those which are in beta version, but also known bugs.