If you’ve had a Microsoft Live account (SkyDrive, Hotmail etc) for a while you are classed as a “loyal” customer and will be grandfathered into their 25 gigabyte storage accounts if you act now. You must claim your 25Gb, even if you’ve been using it for years, otherwise you will be downsized to the new 7Gb limit (which all new subscribers will be offered instead of 25Gb!)
The 7Gb value is apparently to bring it in line with what most users actually use. Just 0.06% use more than 7Gb apparently. Coincidentally, 7Gb is approximately the same storage space you get with a Google account and Google is just about launch an official version of Google Drive. (Actually, looks like GDrive will be 5Gb not your Google Account limit, presumably that’s going to be in addition to the space you get for email).
Meanwhile, DropBox, which only gives users 5Gb, but you can boost that through an affiliate promotion is going to make their system sharable even to non-Dropbox users, which will facilitate file sharing no end.
PS I prefer Wuala. It’s Swiss-based and like a Swiss bank account is beyond the reach and prying eyes of the US Feds. If you have a Lacie hard drive you get a boost to your 5Gb initial free storage on Wuala. Moreover, the cloud part of their system has no access to your unencrypted files, unlike, SkyDrive, DropBox, or the impending GDrive.