bus mastering and MSI 6119 Help please

[grips]

After I installed my G400 32, I noticed that my computer would crash/freeze much too ofter. I thought it would be a good idea to buy an new drive and rebuild my system. Unfortunately, a fresh start did not solve my problem.
Reading posts on this message board, I temporarily "solved" my problem by disabling bus mastering. I realize that this is not the proper solution. These are my questions:

How much of speed decrease does shutting off bus mastering result in?

Are there any other procedures that i can try to correct this problem?

Below are my system specs. I've installed all the latest bios and drivers for each.

Microstar 6119
Quantum 10.2 gig HD (ide)
Maxtor 27.2 gif HD (ide)
Diamond Fireball 20 Scsi card
toshiba 32x scsi cd rom
Yamaha 4x4x16 scsi cd-rw
Maxtor g400 32meg
Ati TV Wonder
SB Live Value

Note:
Ive had these problems BEFORE I installed the ATI Tuner card.


Any help would be greatly appreciated.

Thanks