http://windowslive.com/SystemRequirements
You can access Windows Live online services with your favorite Web browser. To take advantage of Windows Live desktop tools, make sure you meet the minimum system requirements.Component Requirement
Operating System Microsoft Windows XP SP2 or later, or Windows Vista
Windows Live programs do not support Windows XP Professional x64 Edition. Windows Live Family Safety does not support 64-bit editions of Windows.
Processor Minimum 800 MHz processor
Memory Minimum 128 MB of RAM (256 MB or more recommended)
Browser Internet Explorer 6 or later
Internet connection Internet functionality requires dial-up or broadband Internet access (provided separately). Local or long-distance charges may apply.
Display Minimum 800 x 600 screen resolution (1024 x 768 or larger recommended)
Prerequisite software These components are required and will be downloaded and installed if they’re not already on your computer.
For Writer:
Microsoft .NET Framework*
For Photo Gallery:
Windows Imaging Codecs*
SQL 2005 Compact Edition
*This component is not required when installing on Windows Vista.
with your favorite Web browser
My favorite browser is Opera…
Hmm… Seems like they don't have the concept of favorite browser not everyone loves IE
D. Gates writes:
Opera’s my main browser too, and it seems to work fine with Windows Live, at least on 32-bit Windows.Opera’s my main browser too, and Windows Live Family Safety messes up its formatting on my 64-bit Windows 7 beta machine, which I see now is not supported. Considering that my web filter, OS, and browser are all pre-release or unsupported, I guess I should be thankful it works as well as it does.