Honestly I do not know how to raise the priority of Rosetta on Win98 but I do know that it is

1) Dangerous to your machine
2) likely to make the machine virtually unusable for anything else and
3) Unlikey to make any significant difference in your throughput.

This is unless you have some kind of trojan that is hogging resources. In that case the far better solution is to get rid of the trojan.

If you are interested in a discussion of why raising the priority of Rosetta is a dangerous thing to do, I or someone else will explain it.

Thank you for your quick and complete answers to my question.
I will follow your advice and won't change the priority of Rosetta.

I have not the necessary knowledge to understand how win 98 thread priorities works (just to let you know, i've been studying statistics), but thank you anyway.

Andrea