More memory, or more processors

We are running a heavy-duty aplication under Informix OnLine 7.13 os a Sun Sparc 20 with 2 x 75MHz processors and 160M of physical memory. Budget has been set aside to purchase a hardware upgrade, viz an Ultra 4000. The specification was to have been 4x250Mhz processors and 1G of memory. A consultant has done a sizing exercise on our current configuration and, as a result, we have upgraded it to 384M of memory. The server is showing significantly lower page scan rates, so I think this has been of benefit. The consultant is now recommending that we configure with 1.5G of memory and just 2x250MHz processors. Does anyone have any experience of which OnLine is likely to better utilise; 0.5G of extra memory, or 2 additional processors? Any comments gratefully received. Neil Truby Chase Manhattan Bank Bournemouth, UK neil.truby@chase.com