Is a multiple SUMIF formula possible in Excel 2003?

After searching the forum it seems that what I need is SUMIFS, but that's not available in my rather dated version of Excel.

I need a SUMIF formula that will return a total from Col.I only if specified conditions are met in both Col.J and Col.K.

I've attempted to attach a copy of the worksheet, which is a list of wiring required to make up a harness (loom) for a car. Cell W21 contains a single SUMIF formula, but it needs to be combined with the formula in X21, in other words both cable size (Col.J) and colour (Col.K) coincide.

Any help with this will be greatly appreciated.

Richard