Increasing the Signal Strength

I'm using a D-Link G132 wireless adapter with my parent's D-link A&G wireless router.

My question is, are there any ways to increase the signal strength through program wise or what you may suggest?

The current problem is that I can only get a "Low" or "Very Low" setting and even then I will have problems with the link. The router is not far away. It's on the same level and just down the hallway on the left I guess is a good way to discribe it.

Beware of the WRT54, they changed models without telling anyone, and the new model has half the memory and a weaker processor, for the same price!
Check tomsnetworking.com for the details on how to find a good model.
Direct link:
http://tomsnetworking.com/2006/06/08/linksys_wrt54g_v5_really_is_a_lousy_router/