I re-installed XP today and decided to try out running as a standard user, not as an administrator. (I did only switch once I got Office and Visual Studio installed.)
When I do need to be admin, I use this tool: link This prompts for the Administrator password, then mine, which adds me to the Administrators group for the context of a command prompt. Anything I run from that prompt runs with my increased privileges.
I'm going to give it a week or so and see how I get on.