You might want to consider updating to 2010.

My son makes his living as a free-lance technical writer and Excel consultant. He tells me that there is a huge performance drop (speed-wise) between 2003 and 2007 when you have very large Excel files, particularly with lots of conditional formatting. Also that if you use conditional formatting there is an egregious bug in 2007. 2010 brings the speed back up to 2003 standards, and fixes the conditional formatting bug.

tanstaafl.

ps: The bug... In every version of Excel except 2007, when you copy cells with conditional formatting to a new location, the copied cells over-write any conditional formatting in the destination cells. In 2007, the conditional formatting in the copied cells is concatenated onto the conditional formatting in the destination cells. This can cause unexpected results...

He works with a gigantic spreadsheet that he created, ~7MB containing 39 interactive worksheets. Summing up, there are a total of 37,550 rows in 4,905 columns, containing 245,308 cells with data in them, over 100,000 with conditional formatting, with thousands of formulas beyond my comprehension, like this one:

=IF(BeamMaxDmg<>"",ROUNDUP((VLOOKUP(Cmp_Beam_Pri,Priority_Level,2,FALSE)
*VLOOKUP(BeamMaxDmg,Beam_Dmg_Max,2,FALSE)),1),0)+IF(TorpMaxDmg<>"",ROUND
UP((VLOOKUP(Cmp_Torp_Pri,Priority_Level,2,FALSE)*VLOOKUP(TorpMaxDmg,Torp
_Dmg_Max,2,FALSE)),1),0)+IF(MissileMaxDmg<>"",ROUNDUP((VLOOKUP(Cmp_Mssl_
Pri,Priority_Level,2,FALSE)*VLOOKUP(MissileMaxDmg,Missile_Dmg_Max,2,FALS
E)),1),0)

Actually that's one of the easier ones, wait til you see the ones using the Indirect function with named range lookups. Gaaahh!

db