You don`t say what OS your friend is using on the laptop but assuming it`s XP I could understand the long boot up time. A firewall just adds to the programs loading at start up. Doubling up the RAM would improve it significantly but these days it is almost as cheap to add a 512Mb stick alongside the original. (Check for compatibility first)
I would also suggest a fresh re-install of the OS would make a difference - Back up all data and return to factory settings. This will get rid of remnants from old programs. You could also look at their start up programs in msconfig and reduce the number of unnecessary ones.
In your case, and assuming you have Vista, I don`t think the addition of a firewall will make any noticeable difference.
You can have as many spyware programs as you like but my personal opinion is that two is sufficient. I am not convinced that Defender is one of the best so pick from Spybot S&D, Adaware, Super Antispyware or A Squared.