I know where you are coming from. I did IT in college for two years and difficulties meant I lagged behind a bit. I work at an IT firm now and I found the best possible way of learning IT is to do it in the following steps.

Learn about fixing and upgrading the PC hardware wise but dont go to deep into it. Knowing how to make and configure one for now is fine.

Then get some "CORE" knowledge to build on. (TCP/IP) is good for this. once you understand more about newtworks, keep studying the PC working ect and build a knowledge of OS's. choose like WIN 98 UNIX XP Win 2k NT and so forth.

hope this helps a bit its simple I know but thats the basics to get you started.