You can, but they MUST be high quality DIMMs, like Crucial, or Kingston (and not ValueRAM either). To run at 133MHz, you may also have to set SDRAM Data Driving mode to Strong in the BIOS.
The i815E chipset's specification allows 4 rows of RAM (2 double sided DIMMs) to run at 133MHz, and all 6 (3 double sided DIMMs) at 100MHz. You can get around it with what I have told you above though.