Wireless AND Wired on same Machine

I'm running a Wireless/Wired network with a Netgear WGT624 v2 router connected to a Netgear GS116 gigabit switch. Everything on the network seems to be talking to each other alright -- A Dual Core G5, MacBook Pro, Windows XP PC, DLink DNS-323 w/2 1TB Samsung Spinpoints, Netgear SC101, Xbox 360, PS3, Wii, and AirTunes (I THINK that's it).

The problem I'm facing is this: Most of the time the Laptop is connecting Wirelessly, but sometimes I want to jack in with a wire to take advantage of the Gigabit speeds on the GS116. The Macs all play together nicely regardless of connection, but I can't get the PC to see the Laptop when it's wired. When I turn on Airport, it shows up just fine, but w/Airport turned off everything locks up on the PC. So...

In XP's Network Places, do I need a DIFFERENT Network Address for the wired connection to the Laptop? If so, what would it be? The Laptop has the same Name/Share regardless, no?

ALSO -- I've noticed that (according to Sandra) the network speeds I'm getting from the PC to the DNS-323 are about 40MB/sec; from the PC to the G5, about 52MB/sec. When I actually transfer files though, I'm peaking at about 4MB/sec. What gives? From both the G5 and the hardwired Laptop to the DNS-323 those times are hovering closer to 12MB/sec for sustained transfers. When I go from Laptop to G5 it's up to 35MB/sec, and from G5 to Laptop it's up to 50+MB/sec. What is going on? NONE of these times is spectacular, but the whole point of picking up the DNS-323 was FAST transfers. If I'm maxing out at 4MB/sec, what's the point? I'm getting speeds that good to the stupid SC101.

Any ideas? Is there a weak link somewhere in the gigabit network, and why is Sandra reporting numbers other than the real-world speeds I'm getting? FYI, I have the router set to assign a specific IP address to each player -- not static, per se, but reserved.

Thanks!
jg