I would go with Avast! + MalwareBytes.
But before that, if those older laptops are no more needed by anyone, I would manually uninstall what has become unnecessary and all the crapware I can find.
At this point, if you have freed a lot of space or if you never did it before, a defrag of the Hard Disk could help you to squeeze a bit of performance from that older hardware.
Assuming we are talking of a previous Windows OS, MyDefrag is a good defrag tool (
http://www.mydefrag.com/).
Then install and run a complete scan with the two programs above; I think this should be enough to band-aid your situation.