Well nothing really is the same as DivX.
Are you wanting to use it for encoding, decoding or both? XviD can decode DivX 4.xx and 5.xx. ffdshow can decode all versions. 3ivX I think can also decode all (not 100% on DivX3 stuff). Nero I think can also decode all versions, should definatly do 5.xx.
For encoding, XviD is generally quicker than DivX and better quality. 3ivX and Nero should be faster. All should (depending on settings) decode fine via DivX.