Acer MRS600M is not an Acer sound card model... it's an Acer motherboard model. Most of this series of motherboards was used in like the Aspire T671 pc model and all contain the Realtek ALCxxx sound chipset.
This thread (STICKY in our Sound Card Forum) has Realtek drivers... newer versions than what Acer has posted.
http://forums.driverguide.com/showthread.php?t=30800 (post #3)
The newer versions are R1.82 and slightly older than that are R1.71 and cover all REALTEL ALCxxx chipsets. Both versions are posted in the link above.
The one Acer offers is verion R1.53. If the newer versions don't work, then try this original R.153 version here:
http://rapidshare.com/files/75324610...dio_Driver.zip
File Size: 31,963 kb.
Let us know in this thread what works for you. And if your system has a sound chipset different than listed above, you will need to describe it or at least tell us what pc model it came installed in.