I put this one to my wife who is a Nursery Teacher (4 year olds, but has also taught younger ones too). Her recommendations:-

The 'Singing Kettle' series of tapes and videos by Cilla Fisher & Artie Trazise. The videos give actions for the songs.

Canadian singer 'Raffi' - a good source of silly songs.

A & C Black Publications - series of music for children.

Recorded music - Tim Hart and friends 'My very favourite Nursery Rhyme Record'

also the traditional nursery rhymes in general.

We hope these help.

I'll send you my e-mail address, so if you want any other ideas, she's always willing to share.

Good luck

Brian