Security Precautions - Connecting Company Laptop to Home Network

Need suggestions on security steps when (or before) connect wife's school issued laptop to our home network. It'll be wireless.

Main concerns: over years have learned many public schools' security measures & practices are behind times; AND teachers (on the network) d/l a LOT of junk.

1) Steps to minimize chance of school laptop infecting our home networked computers when she has to use our internet from home.

2) Risks (if any) of putting our home network password on school laptop. If stolen, I'd immediately change our netwk PW. May be other risks I'm unaware of?

Haven't had time to learn about this school's security software, practices etc.
School laptop has XP Pro SP3. She has limited user acct, but could get around that if necessary.

Home network has Linksys WRT54GL, w/ WPA2-P, TKIP +AES, w/ VERY strong PW.

My home desktop uses Vista x64 SP1 - usu running a limited user acct.
Her personal laptop is Vista 32. Both have latest KIS - always up to date.

Suggestions or links to articles / posts would be appreciated!