For some reason I've long forgot, I've never been really comfortable trusting Panda.
I would likely prefer Trend Micro over Panda or say McAfee so IF you have an already paid subscription to it I would likely choose to use it up (assuming it hasn't caused and issues w/ your machine).
MSE is surprisingly good for a free product(absorbed Giant A/V A/S, if memory serves, which was also quite good) though I've seen comments that it's not quite quick enough on some specific trojans catching 1st gen of some but not 2nd gen of same or Zero day ones. Not sure if it lacks heuristics/behavioral detecting which would lead to such conclusion. IF you didn't have a PAID one available, I'd likely suggest MSE.
Always download & save any removal tool offered by whatever A/V A/S you chose to try at same time as your main program d/load and run it before installing another program to prevent possible corrupted install of the new one.
I wouldn't count of just ONE program to catch all (they won't) so a couple of "On Demand" scanners (free) or say Spyware Blaster/Spyware Guard by Javacool wouldn't hurt & update/run several times per week for peace of mind.
Sadly you didn't include info on OS/SP/Browsers used etc. so take above w/ salt re: compatibility to you & your system. Good Luck!
I have a copy of Panda Pro and Trend Micro Anti-Virus + Anti-Spyware. I was wondering if I should use one of those, if so which one, or use Microsoft security Essentials.