Help with choosing a hard drive for a home server

I apologize in advance for the question topic.

Having bought Zotac ION, about which I wrote in the previous review , I installed Ubuntu 9.04, and started playing with different possibilities and generating ideas on the development of a home server into a certain system of an inexpensive "smart home" and ... just now got their hands on the simplest, installation and configuration Samba Raised and customized for this article . Everything started with a whistle ... and ... here it was that the Great Lord Oblom was waiting for me, but he arrived on time, so ...

What is available:
Iron:
Motherboard: Zotac IONITX-A (N330, NVidia GF 8400M GS);
Screw: Western Digital Caviar SE WD2000JS 200GB 7200 RPM 8MB Cache SATA 3.0Gb / s 3.5 "Hard Drive
Network: some kind of nVidia Ethernet controller 1Gbit / s
RAM: 2Gb OCZ 800MHz
OS: ubuntu 9.04 desktop edition
Network at home: DLink DIR-615 + to which, via Wi-Fi (g-54Mbps), up to 4 laptops can be connected at the same time and the home server assembled on the cord is connected to it.
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And what is the problem actually?
Yes, that’s actually the speed of the problem. Video in DVD-nifiga format does not look, but if only DVD, from two computers (wife and father) is already problematic, simultaneous viewing of movies in the usual mpeg4, not to mention the fact that at this moment also torrents flow from the external network syudy at speeds up to 8Mbps. Yes, and how I would also work, and I would like to listen to music in my headphones, and considering 100Mbps in Ukraine at home and at work, I would also like to listen to music directly from my home server. Those. these are persistent data streams ...

So it came to life ... rested not on the Ethernet channels, not on the network boot, but on the hard drive ...

I understand that the old hard drive that I have, but I'm a little behind the iron issue, and ask for help from the Habrasoobschestva . Now I want to buy a pair of 1TB winchesters, but I don’t understand at slaughter which parameters need to be watched, and generally what you will advise from winchesters. Seagate after lazhi with his series 7200.11 - somehow dumb to take. WD-shki? Or maybe some more correct spacing to do?

In general, I want to get:
1. A separate working web server and in general business tasks (well, well, I'll leave a 200GB screw for the system);
2. 2 winchesters on 1TB - for storage of home videos and audio collections, with the simultaneous viewing by two people of the video in mpeg4 (although preferably DVD, of course) + one user so that he can listen to the audio (mp3, but mostly FLAC). It seems to me that this issue can also be solved somehow more correctly by codecs with some kind of software, or with some other streaming software or something else?
3. Download in the tracker at a speed of at least 4 Mbit.

Thanks in advance.

Update:
Although it is incorrect, I also think so, asking questions that I asked here, but the result was help from Adeptice with Wi-Fi. As a result, it saved that money and time. Having installed the correctly chosen antennas on my router, I finally received a 100% signal within a radius of 20 meters, even through 4 walls of shell limestone, each 55- 60 cm. This time, and the second decided on the hard drive and purchased it. Soon I can accomplish the full setup from scratch of a small home server. Please do not minus it right away, like what everyone knows, in fact there is nowhere information gathered together, you have to gnaw here and there ... it took more than one hour to select and reinstall and try different distributions ... :)

Thanks again to ALL who helped. :)