Sometimes I check MSCONFIG's Startup tab to see what programs are loading at startup (Start Menu / Run / type MSCONFIG / press ENTER / click the Startup tab on the far right).  The only thing I see there anymore is the Zone Alarm client (zlclient).  It's a nice short list, which is definitely a good thing.  A bad thing would be to look there and find entries for spyware, adware, trojans, or some other piece of crap that parked itself there without asking.

Even relatively harmless Startup items may not be welcome in the Startup list.  I'm thinking of the little System Tray tools that come with software for video and audio cards, or the helper/agent applets that programs like QuickTime, Office, Winamp and Real Player will shove at you if you let them.  These startup items can increase boot times, slow down your system once it's booted, and generally be a nuisance and a waste of resources, not worthy of the checkmarks next to their names.  If you're having performance problems or other weird happenings with Windows XP, you just might find the cause(s) hanging out under MSCONFIG's Startup tab.  Don't be shy about removing checkmarks; if something stops working or stops working properly, put the checkmark back on the next reboot.

At PC World, there is a chart headed 15 Icons You Can Dump... to quote, "You can shut down these system tray applets, or delete or hide them, without fear of disabling a critical Windows function"

A WINXPNEWS issue provided this link at Computer Hope, which shows and explains many System Tray icons and what software is associated with them.

Sysinfo.org has a huge list of startup applications and descriptions.  There are thousands here!

More startup information (I lifted most of these from the Windows 98 page):

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AnswersThatWork has a section on Task List Programs.  Another excellent startup resource is WinTasks Process Library.

Autoruns, Startup Control Panel and StartupRun are good alternatives to MSCONFIG.  They peer into the more out-of-the-way crevices of Windows, without requiring you to go into the Registry with tweezers.  MSConfig CleanUp will let you clean out leftover items that can remain, even after their associated programs have been disabled through MSCONFIG.

If you'd like to add a few ounces of prevention to the mix, Startup Monitor, WinPatrol , and Startup Mechanic are three more programs to consider.  Don't try running more than one of these at once.  Think of them as firewalls for your startup process.  Among other features, they warn when programs try to insert themselves as startup items, and let you choose whether or not you want that to happen. ..."

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While I'm on the subject of unwanted Startup items like spyware, it's important, now more than ever, to have spyware/adware/scumware removal tools installed.  The two most mentioned free programs are Spybot Search & Destroy and Ad Aware.  Use one or both, preferably both, one to get what the other might have missed.  Also visit SpywareInfo to expand your knowledge on the subject and to take advantage of the tools and know-how that are there.

In MSCONFIG, you'll notice that Services aren't lumped together with startup items, which to me makes sense.  I've read that Services shouldn't be enabled or disabled with MSCONFIG anyway (see this FAQ at Black Viper).  MSCONFIG has a category for these, along with BOOT.INI, WIN.INI, SYSTEM.INI and General.  I decided to see what if anything would happen if I unchecked Process SYSTEM.INI File and Process WIN.INI File ... so far, nothing bad.  I had read someplace that XP Pro could do without them and it can, at least on this computer.

Anyhooo, with the exception of the checklists under General, BOOT.INI and Startup, I don't bother with MSCONFIG's other tabs.  I keep a lid on Services by using Administrative Tools in Control Panel.  And I'd rather use Edit.com (the old DOS editor) to keep control over BOOT.INI.  But that's a personal preference... there are other ways to view and manipulate BOOT.INI, as you'll see.

More on the System Configuration Utility:
    - What is MSCONFIG? (NetSquirrel.com)
    - TASK LIST PROGRAMS - including WinNT4/2000/XP/2003 Services (Answers That Work)
    - How to manage Windows Startup (Windows XP Fixes, Tips and Tweaks)
    - Clean up the MSCONFIG startup tab listings (Windows XP Fixes, Tips and Tweaks)