... Model TS30H Inspiron 3000 M266XT Notebook....
Mine is the TS30I, Compal Computer Corp. of Taiwan
I put in 2-256MB PC66 RAM modules in the user accessible slots. They were from a Dell Inspiron 8000 & they worked. With the 32MB module buried inside the 1st hidden slot, that's 544MB.
Windows 2000 preceded Windows XP.
Win2k does not support IE7, 8, etc., so you're stuck with IE6 or FF. FF does not replace IE, you can't uninstall IE6. You just have to start using it to get used to it. It's a browser, start surfing.