or if you have a fast video card, use what ever settings for it you want, the default settings for the eternal SPU and in options (On ePSXe, not ePsxecutor) force PAL.
I have a gefoece 2 gts, so my resolution is 1280*1024 32 bit with nice settings plus Frambuffer effects turned on (not FVP)
I also have a SB live so the default settings for the eternal SPU work nicely
everything is 100% smooth.
Some notes about MGS.
The sound buffer (in eternal SPU) is really dependent on your sound card; some cards will operate as low as 1, while others (such as mine) operate best at a setting of 11. Probably you'll want to keep it lower than 20...over that and the sound will have a tendency to lag.
Also try pete's Dsound 1.12, there's less setup involved.
Also enable PC FPS calculation under the special game fixes in pete's GPU plugins; doing this will help sync the sound better, and reduce some "slowdowns" in cetain areas. And set offscreen drawing to 3 (not 4).
And lastly, if you want to see the mdecs I strongly recommend that you download ePSXe 1.0.1 to play this game. And switch to ePSXe 1.4.0 to get past the disc change.