The biggest problem with range extenders is that they tend to interpolate missing data. That means that if a packet is dropped here and there, the range extender will fill in the space with what "should" be there. The problem is, that it creates a margin of error, and with the primary job of the extender being to amplify the signal, it amplifies the error and creates a large space of rubbish data.
That's why I would avoid them.

You'll have a hard time finding an 802.11e router, because it's only a proposed change to the 802.11g standard.

What is the model of router that you're using?
I only use my D-Link DSL-G604t router as my AP.