I have a PC running with a 2GHz P4 and 1GB of RAM. The use of my
Physical Memory jumps from 380MB to just over 1GB when I open any of
the following players: Windows Media Player 10, Nero Showtime (part of
Nero 7 Ultra), WinDVD 7, ATI FilePlayer or the ATI TV program (both
came with my ATI All-In-Wonder RADEON 8500DV). This happens by just
opening the program, even before I choose to play any audio or video
file. Memory usage stays up until I close the player. Then it will go
back to 380MB.

This issue doesn't occur when I use: QuickTime 7, iTunes or VideoLAN 8.4.

Obviously the issue is related to some characteristic all the first
programs have in common (something associated to the use of DirectX
maybe?).

So the question is this: 

How can I avoid using almost 600MB of my otherwise abundant Physical
Memory every time I try to listen to music or watch video on those
players, while using other applications in my PC, doing some
productive work :-)?

Thank you!