Help Find XP Pro Flaws, Errors and Network Hacks! - Go on!

I am currently an ICT student at a Sixth Form College in the UK. The ICT department hands out chocolate bars if a flaw can be found in there 'secure' network user infrastructure. I have already pointed a few errors out, and earned myself some tasty bars of chocolate, however I lust for more. The LEA (Local Education Authority) provides the internet connection to the Sixth Form, so they will have an external filter for the internet which I obviously won't be able to alter. The internal internet filter is controlled by 'RM SafetyNet Universal' (http://www.rm.com/Primary/Products/Product.asp?cref=PD331310), now this can be bypassed using a proxy, which I have already done. I would be grateful if anyone could point out, or instruct me on how to take advantage of flaws in networks and Windows XP. Third party software can alse be used.

Thanks!
Liam