All computers are different, and all users have different needs, so giving a definitive answer is impossible.
Are you talking about start-up software in your Start > All Programs > Startup folder, or in XP's MSCONFIG > Startup tab, or are you interested in Services and Processes?
What you need in the MSCONFIG Startup tab are, firewall, one anti-virus, and one anti-spyware utility. What else you need is simply down to what you want to load up when Windows starts.
Will removing items make your computer faster? No. That depends on your computer specs, (you didn't say), such as processor speed and how much RAM you have. But removing unwanted items from startup will improve how quickly Windows boots up to its 'ready for action' state, eg, everything loaded, it is now ready for whatever you want to do.
As to AOL, what is it? If it is AOL's web site portal that opens in a browser, then do you really need this to load at startup? If not, just wait for Windows to load fully, then open your AOL browser and connect to their web site.
Which items are absolutely necessary at start-up. Will removing items make computer faster. I have Windows XP. DSL modem. Also AOL seems slow to start. Is that AOL or my computer. Thanks for any help.