Wireless Range Extender/Expander Compatibility

I need to extend/expand the wireless range of a Motorola WR850G (802.11g) wireless router. This will have to be with a range extender/expander rather than an access point since no Ethernet cable is available in the necessary area. The distance is also too great to simply use an enhanced antenna system.

Does anyone have experience with an extender/expander that will be compatible with this Motorola model? I understand there can be compatibility issues between routers and expanders. For example, after I worked with a Linksys Model WRE54G Wireless G Range Expander for several hours (and talked with two support reps) a senior Linksys support person told me that the Linksys expander is not compatible with the Motorola router.

Any suggestions will be appreciated. Thanks.