I've seen modern 450 megabit/s 802.11n (3 spacial streams, MCS 23, 40MHz-wide channels, short guard interval, LDPC) get 350250 megabit/s of TCP throughput within the same room (~5 meters), on a clean channel pair, with sub-3ms latency. So that's about a thirdquarter of what you'd get from 1000BASE-T.
It's not hard to get Fast Ethernet-like throughput even on yesteryear's 802.11n gear such as the old 300 megabit/s stuff that came out in 2007. 150 megabit/s TCP throughput is possible.
If takes you 30-40 minutes to copy 2 GibiBytes of data from your NAS, then you're only getting 7-10 megabit/s, which is sad even by 2002-era 802.11a standards. You need to troubleshoot your network.
Move it to a clean channel pair and start paying attention to your MCS index and data rate. Maybe you need an AP closer to where you use your laptop.
You might also have TCP tuning problems on your NAS or your laptop. What file service protocol are you using? SMB? NFS? AFP? What TCP window sizes are your connection endpoints using?
Update based on Justin808's update with details
Only Apple's latest "Thunderbolt" MacBook Pro's that were just released in February 2011 are capable of 450 megabit/s (3 spacial streams) operation, so your 2009 model tops out at 300 megabit/s signaling. So in ideal conditions, you could see 150 megabits/sec TCP throughput. You're right that that's not anything like the 950+ megabits/sec TCP throughput you could see over 1000BASE-T, but it's faster than the previous generation of Ethernet.
If you bought your Time Capsule at the very end of 2009 or later, you might have a 450 megabit/s capable Time Capsule, but you would need to upgrade your MacBook Pro to get those speeds.
I think you need to double check exactly how long it really takes you to download large files of exactly which sizes over wireless, because 100-200 GibiBytes in 30-40 minutes would be 358-954 megabit/s throughput, which is far beyond the physical capabilities of your 2009 MacBook Pro's wireless card. Maybe you had left your Ethernet cable plugged in and you were actually doing that copy over 1000BASE-T? 954 megabit/s is great TCP throughput for 1000BASE-T without jumbo frames.
What is the make and model of your NAS? You said it was 10TB but a Time Capsule is only 2TB unless you've plugged in several external USB hard drives to it, and USB 2.0 Hi-Speed is only nominally 480 megabit/s; in actuality you'll never get more than about 250 megabit/s sustained reads from a hard drive connected via USB 2.0 Hi-Speed, so if your Time Capsule with a bunch of external drives is your "10TB NAS that's got a nice 1000BASE-T connection", you're fooling yourself. So I'm guessing you've got some other NAS box. I've never seen a good AFP implementation in an embedded NAS box other than Apple AirPort Extremes and Time Capsules, so I'm curious.
Signal strength (RSSI) of -77 dBm is poor. It's below the "roaming threshold" of most wireless clients; that is, at signal strengths that low, your client is actively looking for other APs to roam to, so it's periodically going off-channel to scan for other APs to join. I can't account for why you'd see an RSSI this low in a 2-room condo, unless your walls are made of something seriously RF-blocking. But if you're seeing tons of neighors' networks, it's probably not your walls. I suppose it's possible that there's something wrong with your antennas in your Time Capsule or MacBook Pro, like maybe an antenna connector became disconnected in transit. Try setting your MacBook Pro right next to your Time Capsule. You should see an RSSI in the -30's or better (less negative; closer to zero). If you don't at least see something in the -40's when you're within 1 meter of the AP, then it's time to make an appointment at the Genius Bar.
Your MCS of 0 or 1 and transmit rate of 14 megabit/s is consistent with an RSSI of -77. Of course this is all utterly inconsistent with your claim of 100-200 GibiByte files downloaded in 30-40 minutes, unless I did my arithmetic wrong.
I'd turn off Interference Robustness if I were you. Features like that generally sacrifice range for throughput in the face of interference, and with RSSI -77, it seems like you don't have any range to spare.
By the way, when you talked about the "n network" vs. the "g network", I'm assuming you set up your Time Capsule to use different network names for the 2.4GHz and the 5GHz network. I don't like calling the frequency bands by 802.11 amendment letters like a/b/g/n, because 802.11n works in both the 2.4GHz band and the 5GHz band, so which of those is "the N band"? Also, the "b band" is the same band as the "g band". So it's a bit more clear to refer to the bands as "2.4GHz" and "5GHz".
When it comes to maximizing your throughput at range, make sure you've enabled both A and N on the 5GHz radio, and feel free to do B/G/N or G/N on the 2.4GHz radio. Sometimes the legacy A, G, and even B rates can get better throughput at range than forcing your laptop to stick to N-style signaling. Also, somewhere around an RSSI of -65 dBm or less (remember less == more negative, like -66, -67...-95), you'll usually get better throughput in the 2.4GHz band than in the 5GHz band. Of course that might be mitigated by the airtime taken up by your PS3 and your iPhone, so YMMV.
