Problem Defragging in XP
 

My HD is becoming increasingly defragmented and I don't know how to fix the problem.

The problem is that disk defragmenter will not defragment certain files. The majority of them are TV shows or other mpg files (animatrix, various anime). The only non movie file that won't defragment is war3.MPQ. I'm really not sure why, its not even all the movie files.

Thanks in advance for any help.

Yeah, I've had the same issue previously. There are other companies that offer better defrag performance. The only ones I can think of right now are:
Power Defrag: http://www.powerdefrag.com/
and
Disk Keeper: http://www.executive.com/coverpage.asp.

I ended up using Perfectdisk, work really well. Disk Keeper didn't work.