The importance of preschool?

[glbenner]

My daughter just turned 4. She is very intellegant.
She knows her ABC's and can state what words start with what letters if asked such as what letter does _____ start with or What word starts with __.
She counts and does simple addition and subtraction problems.
She can write most of her letters, knows her address and phone number and has a vocabulary of someone much older.

The problem is she does not do well around large groups of children, actually more then 3. She is very comfortable around adults and interacts very well with them but she gets upset around other children if they are loud or rowdy.

Should I put her in preschool? I don't think she will learn much there but I was wondering about socialization.
She is currently in an in home day care setting.
Any thoughts?