Digital BW, The Print

I've been using MIS VMS ink set for some time now with very good 
results. I recently purchased a new computer which uses XP for the OS 
and am running Photoshop CS. My previous system used Windows 2000 and 
PS 7. I had no problems printing sepia tone with Keith's curves. Now 
on my new system all I get is variations of grayscale, no more brown 
tones. I've tried Roarke's curves but get too much posterization. 
Does anyone have any suggestions I might try? 
Thanks in advance

Evelyn