In addition to the other suggestions, make sure that:

1) Join columns are indexed

2) Indexes have the proper freespace and are reorganized / rebuilt as often as needed to keep them functioning well

3) Queries do not do functions on table columns unless absolutely necessary, esp. on indexed columns. For example, instead of:

WHERE YEAR(datecolumn) = 2008 AND MONTH(columnname) = 2

write:

WHERE datecolumn >= '20080201' AND datecolumn < '20080301'

4) Tempdb has at least one data file per processor core

Since you have only one SAN drive, you cannot be using RAID 1 for logs and RAID 5/10 for data. This will affect your performance as well.