well, have you looked at Goarmy.com?
Calvary scouts ride in Strykers most of the time and you gather intel or spy on the enemy and tell HQ everything but you still have gun .50 CAL on top, Armored vehicle and nice high tech equipment inside..Goarmy.com said the strykers can take IED's and RPG's and it would be fine.... This is a good job if you don't want to much action but still want some, and would like to stay in Strykers most of the time. someone told me you have Air Condition in there and you get to have your CD's and books in there and sleep there if you want.....
Infantry will most likely be walking in all you gear, unless they order you to hitch a ride, mostly do firefights, mostly the most dangerous hard job. If you are looking for a challenge and this is your calling, willing to take the hardest job......might have to sleep in the rain, hike for a long while, or face danger a lot......
hmm MP's, they might stay in base patrolling or something to make sure the safety of all men, answer to crimes or whatever happens in Military property, and testify in court. they also secure convoys, basically they are also security. i think they do the traffic checks and stuff in Iraq and Afghan i think........if you want to secure and safe other from crime, looking for law enforcement type job, with all the training from Army.....you could possible be in Cop cars.....