Vista - Routine Maintenance Advice Wanted

Hello,
Well I guess it's best to come right out and explain I'm a basic appliance operator. I read directions, first, as best possible. Then plug "IT" in and go. I try to follow all recommendations as best possible. not to store too much on computer. Don't clog up start up pages. Don't overload desktop with things I don't need...
I keep up with all important updates or recommended updates. (Which almost seems like a daily thing!)
I do disk cleanup about every couple weeks and thought I was Defragging on a regular basis, of once a week. Except this was scheduled in the middle of the night and I'm not usually up and the computer is not usually on at that hour! I turn it off when not in use. Both This Lap Top and My XP running desk top
I think, now this is just a guess but I think that lately the LT has been trying to run it's defrag when I turn it on in the mornings or when I get home at night and check mail. I think causing me lagging response in the units speed and ability. I know a year ago when I checked videos on you tube I could watch a whole video no issue now I can not.
I was also told by a DLS tech that I must also manually clear browser history at least once a week which I believe I am doing now also.
Back to question...I did manual defragment today and it says can take from minutes to hours....Hours as in there where many. I think it took more than 4 hours! I was not running anything else had IE closed. only shows desktop that’s it. And as much as I hate using this word... I assume...then the drive light on the front is still flickering that the unit is working on a project! In this case defragmentation. IF I have been accidentally blowing the scheduled defrag times is it possible that this would take hours upon hours? I didn’t want to shut down the unit if still in progress as I feared it will only then need to start over!
I welcome suggestions. I’m no techy but I try to follow advice as best possible. All seems so intense and new as I just climbed out of my dial up cave a year ago and it's a larger much faster world out here now!!!
I’m now trying to keep this “lag” out of both my units, something I understand sneaks up on one. So any routine maintenance advice to keep all portions of LT clean and clear welcome. Seems I pickup bits here pieces there...
Thank You for your time, and patience with someone fairly low on the tech knowledge scale

Hi bajadreamers, welcome to the forum.
Get Auslogics Disc Defrag from here:Auslogics Disk Defrag - Free software downloads and reviews - CNET Download.com
and have a look at this tutorial as well
Speed Up the Performance of Vista[11]=Performance Maintenance
HTH.