Well, if one Resident Shield from an anti-spyware program consumed this much amount of memory, and then there was a rule that all other anti-spyware Resident Shields had to restrict their Resident Shield's memory usage to that amount, it wouldn't be very fun would it since it might mean a drastic reduction in program functionality and potential.

I'm sure 80MB shouldn't be a problem since you have Windows Vista, which usually provides you with at least 1-4 GBs of RAM. I have 512MB of RAM on Windows XP and TeaTimer runs with no problems. Don't see how it may be a problem with Vista.