Ok, so let me be the first to say the trial version of fraps is a piece of shit, at the very best.
It will only allow you to record 30 seconds at a time, no good.
I tryed wegame, and some other crap excuses for a program.
There is this free one found at
http://zdsoft.com
Records however long you want at good fps, does not make you lagg nothing like fraps, and it quite easy I assume for any computer to run reguardless of specs since it seems to not take up much CPU percentage.
I would go with the zdsoft recorder hands down for a free one that can do everything you want it to do.
Here is an example of zdsoft recording quality, fraps recording quality is just as bad.
http://www.youtube.com/watch?v=ktRRCcqNp_Y