alpha is the finished version. most OS codes start in delta, then gamma, then beta, then alpha. i don't know what "other places" you're getting your information from, but if i were you i'd listen to microsoft instead, they seem to know a little bit more about their OS's than most.
if anybody needs any confirmation of whether or not this so-called "beta" test is worth it, look no further than the windows 7 beta FAQ on microsoft.com. here's a direct, copy/paste quote:
"it’s
not the finished product. Your computer could
crash and you could lose important files. So please don’t beta test
Windows on your primary PC.
Other problems you might encounter include:
[*]
Software that doesn’t install or work correctly, including anti-virus or security programs
[*]
Printers, video cards, or other hardware that doesn’t work
[*]
Problems accessing corporate or home networks
[*]
Files may become corrupted
[/list]
Bottom line: Please carefully balance the risks and rewards for you of
trying out the Windows 7 Beta before you install. Before installing and
using the Beta, download and review the
Release notes.
They provide important information that you should know before
installing and using Windows 7. You should familiarize yourself with
all of the known issues in this document prior to installing the
software. For example, the release notes describe a bug in which MP3
files may become corrupted and provide information on mitigating risk."
seriously guys, if you don't know what alpha code is, you should probably just wait. running unfinished OS's is not worth the risk if you don't have the money to replace your PC.