Myself, I have 1.5GB of RAM and I set my pagefile to 1024 minimum and 3052 maximum... but then again I use programs that use a lot of memory, especially the way I use them...
512MB of RAM should be plenty for web surfing... even 256MB should be ok. As for the pagefile, it mainly depends on how much hard drive space you have available. There's no point in setting it really small because you'll just get errors. Setting it large doesn't kill performance either... if your computer needs 512MB in virtual memory, it's going to want 512MB whether the max is 256MB or 1024MB (although you shouldn't need that much for virtual memory either... I'd say 384MB Initial and 768MB Maximum)