How do I get and install customized themes for Windows XP?
You will need to download a patcher/replacement for the UXTHEME.DLL located in the WINDOWS\SYSTEM32 folder as Microsoft only allows digitally signed themes. This patch will remove that restriction. You can find it by performing a Google Search. As for themes, you can try ThemesXP (known to have adware) or DevianTart or ThemesWorld. Remember to use only .THEME files, not EXEs as those could be malicious. You might have some trouble as most downloads are meant to be used with Styles XP (a commercial program), and most websites don’t reveal which method a theme uses – StylesXP or Windows Theme..