use the taskmanager performance. that thing never lies. never ever. so you should check how much of your memory is being used, if there's any burned up stuff like that. and i personally like to keep my machine under forty degrees. if it's starting to get hot i'd just take off the case cover and put an oscillating fan to it.
get windows defender too and don't touch the popups. my brother got this stupid thing called spyware quake on my computer and it took forever for me to get rid of it. the easiest way really is to just download the trial version of prevx1 and let it scan. it's a 30 day trial i believe and it lets to delete stuff without having to pay