Drow are EL +2, so Experience requiresments for levelling are::
LEVEL ... Normal .......... Drow ...... Difference
1 .................... 0 ........ 3,000 ............. 3,000
2 ............. 1,000 ........ 6,000 ............. 5,000
3 ............. 3,000 ...... 10,000 ............. 7,000
4 ............. 6,000 ...... 15,000 ............. 9,000
5 ........... 10,000 ...... 21,000 ........... 11,000
6 ........... 15,000 ...... 28,000 ........... 13,000
So as you can see, each level "costs" more for Drow, or other EL-adjusted races, by a (marginally) wider and wider gap. In other words, the Drow, or any other EL +2 race, should consistently be 1 or 2 levels behind an "EL+0" character, a la the standard PHB races.