Where do I find the abbreviation definitions and their meanings listed in msconfig?

Google them. The list is endless since any program can set itself to run at start up.

You can also do a Search for the filename on your system. This will tell you what folder they are in whch may give a clue as to what they are. Also, if you find the file, right click and check its properties.

Good places to check out processes:

Svchost and more... the PPedia Process Library (http://www.ppedia.com/)
File Research Center - Find out what's really running on your PC! (http://www.fileresearchcenter.com/)
Task List Programs - AnswersThatWork's famous Database of Windows Task Manager Processes, Windows Startup Items, XP Services, Vista Services, Process List (http://www.answersthatwork.com/Tasklist_pages/tasklist.htm)
Welcome to the File Database! (http://www.kephyr.com/filedb/index.php)
What Process? Process Library - Identify & Manage Processes (http://www.what-process.com/lists.aspx)
Windows Process Information (http://exelib.com/)
ProcessLibrary.com - The online resource for process information! (http://www.processlibrary.com/)

Best way to control startup: BillP Studios: WinPatrol (http://www.winpatrol.com/)

Places to check files for baddies:
VIRUSTOTAL - Free Online Virus and Malware Scan (http://www.virustotal.com/en/indexx.html)
Online malware scan (http://virusscan.jotti.org/)