Configure Vista to connect to nearest AP

My wireless network consists of a Netgear WGR614 wireless router upstairs where it connects to my DSL provider, and downstairs I have a Linksys WRE54G wireless repeater to help improve the connection for my wife's PC in the downstairs office. From what I can tell, I have to configure the repeater with the same settings (SSID, channel and security settings) as the Netgear so it can connect to the Netgear as a wireless client/AP. Unfortunately, I think I may be creating a problem with my new Vista computer.

The Vista system is in the same room as the Netgear (perhaps 20 feet away). When I browse wireless networks to connect to, I only see one network with my SSID name (I have both the Netgear and Linksys broadcasting the SSID). When browsing, the signal strength is 'excellent', but when I tell Vista to connect to it, the connection strength is 'good' at best (mostly rates at 'fair').

I couldn't figure out why the signal strength of the connection would be so poor, given the proximity to the Netgear. But when I log into the Netgear admin interface and view the attached devices, the MAC address for the Vista PC is always the Linksys repeater downstairs, not that of its wireless card. I've tried repeatedly to reconnect, but I keep ending up with the more distant Linksys instead of the Netgear just across the room ... that's a mystery in itself. I did verify that if I unplug the repeater, then Vista happily connects to the nearby Netgear (the Netgear shows Vista's systems wireless MAC as attached) and signal strength is 'excellent'.

So the basic question is if I can configure Vista to only connect to a specific AP? The Vista system is a desktop so I'm not going to be mobile with it so I'm fine with "hard-wiring" it to the Netgear in the same room. Related to that, is there a way with Vista to see the MAC address of the AP it connected to? I know some add-on wireless tools like Odyssey will show you, but can you do the same with Windows?

On a broader topic, am I creating a problem with the repeater since it has to have the same channel as the Netgear (are they interfering with each other)? It doesn't seem like I can change the settings on the repeater because then it can't connect to the Netgear as a wireless client.

Thanks in advance.