Sufing Kids

Do your kids already get on the PC and surf the net to kid-friendly websites? Do you allow them PC access to play age appropriate games? I am just wondering as Sweet Girl doesn't get a lot of PC time, really none at all. She has her VTech thing where she can play some video games but it really doesn't hold her attention very long.
But I'm wondering if we should be allowing her to become more PC literate at this stage? She is almost 4. Is it too early? We do have a desktop but it's in our wonderfully unorganized closet and the monitor is still wrapped in bubble wrap.
I know they have a PC in her preschool class and they do some activities on it. But I'm not sure how much, I will have to inquire.
She is a lover of real books, so I don't want to replace the PC with her love of reading because she views the PC more exciting.
I am sure with all things kid related there is a balance. I will admit I am not very good at the balancing act. I am always out of balance for some reason! Even with all that "core" conditioning I've been subjected to...
Oh the joys of parenting...It is my biggest challenge yet.