not to degrading McAfee but i'd suggest you to uninstall McAfee and install a more lightweight and reliable antivirus and you could have it for free they are Avg, Avast, and Avira.
What does it mean by essential software ? i think essential to me might not be essential to you.
But lets take it to software category...
1. Office application (eg. OpenOffice, ThinkFree Office)
2. Antivirus (AVG, Avast, Avira)
3. Image viewer (XnView)
4. Picture editor (Photscape, Paint.net, GIMP)
5. movie player (VLC, Mplayer)
6. Dictionary (theSage)
7. Download manager (FDM)
8. Network bandwidth meter (NetMeter)
9. etc..
all of it you can have it for FREE!!!
since there are lots of opensource and freeware
you might interested to take a look at http://www.purelegalcomputing.com
search for category, i tried it my best to only post credible free/opensource software.
Good luck with your new PC, remember stay away from piracy :)