Kevin
Relative speed will depend mostly on the server you use for SQL Server, what else is using it (is it a file server as well? Are other busy databases in there?), how busy your network is, how static your data is, how you use SEEK.
In general you should feel fairly confident that SQL server will not be dismayingly slower, in many areas you should reasonably expect *visible* speed improvements. One piece of advice, pay the outrageous price to get a SQL Server "expert" to review your needs, specify hardware and help you install. You can do it all yourself but there are lots of tricks and poorly-documented tweaks that can make an unbelievable difference.
If you are using indexseek then SPT using EXISTS() should allow you to achieve *very* good performance. You will not see the client cacheing that contributes so much to VFP's speed but it will be FAST. You could also consider a SP especially if you need to do lots of indexseeks at once.
Summary: in my experience SQL Server is as fast or faster, as you would expect from a server-based system where I'll bet the server hardware is much better than that you used for VFP.
HTH
Regards
JR
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1