upgrading processors

We have a few days to spend the rest of our budget this year. With a RS/6000 and two - 166 Mhz processors, one 5 Gig database spread across 6 disks, would it be better with IDS 7.31UC3 to upgrade our two 166 MHZ to two 332 MHZ or buy 2 more 166 MHZ for a total of four 166 MHZ processors? Our load is mostly queries, I would say 60%, and 35% is updates and inserts. 5% is compiling and misc. Any suggestions? Thanks so much, you all have been really great in responses in the past! Cathy Geier Northwestern College St. Paul, MN 651-631-5284