You can donate whatever you want to. There is a box that asks you to place the amount you wish to donate and how you wish to donate it. Like any charitable organization, they usually ask for special amount (in this case $24 , Jeff Gordon's car number) but if all you can contribute is $5, they'll take it, with gratitude.
As far as AARP losing their butt over this deal, I don't think so. AARP will come out fine. And so will HMS/Jeff Gordon. Although far from having knowledge of the financial arrangement, HMS/Jeff Gordon most likely is contributing a large portion of the sponsorship to AARP and writing it off their taxes as a charitable contribution. If so, I say, good for them!
So, with this information of how and how much to donate to the hunger program, can we count on YOU for a donation of $24?
Okay, how about we all consider how much we spend in one week on eating out (fast food and Twinkies count) and beer and skip those luxuries for that one week. Wouldn't it make you feel good to know you made a difference some older people had food to eat and that was all you sacrificed.
A fast calculation (no cheating) and what are you waiting for? Do it !