A quid is a slang term for the British pound. So currently, 1000 quid (or 1000 pounds) is about $1500 US dollars.
Sidebar is a theme feature introduced with Version 2.2. It's basically a vertical column provided by a theme for displaying information other than the main content of the web page. Themes usually provide at least one sidebar at the left or right of the content.
Windows Sidebar originated in a Microsoft Research project called Sideshow (not to be confused with Windows SideShow.) It was developed in the summer of 2000, and was used internally at Microsoft. It included a clock, traffic reports, and IM integration.