Sybase to sql migration problem

Hi recently i moved sybase 8.0 database to mssql server 2000,here i actually got problems after done megration we tested some quaries and stored procedures they are running very long among that one quary is running like 6 hours priviously it was running on sybase server for 45 minutes what would be the major blow for this problem

SRJ2005

we did reindexing on all tables and we missed re-compile stored procedres ()

SRJ2005

wasn't sybase 10 or 11 contemporary with SQL 7,
so sybase 8 would probably be comparable to SQL 6

in which case i would think the issue is more likely to be with
the change from a basic optimizer to the cost based optimizer in s2k
even oracle had huge problems with cbo that many people stuck to rules, until the more recent versions.

i would look the exection plan, run the query with SET STATISTICS PROFILE ON
then look for expensive ops that probably should not be

also
SET STATISTICS IO ON
SET STATISTICS TIME ON
exec -- query

for the plan copy the plan info to excel,
for the IO and TIME, copy the messages to a text file