Nope...you can't do crap with silver apparently. Here's some stuff about it
Xbox Live Silver (free)
Create your gamer profile: Ok, you get a unique ID to identify yourself on the Xbox Live network. Sweet.
Create and maintain a friends list: You can chat with Xbox Live friends just like any Instant messaging program.
Access To Xbox Live Marketplace: You'll be able to download game demos, skins to customize the look of Xbox live, game content, and arcade mini-games. Some downloads will be free (demos, trailers) and others will be premium (arcade games).
Xbox Live Gold (as low as $50/year)
All the Silver level benefits PLUS:
Online gameplay: You can only play games on Xbox Live if you have a Gold membership.
Exclusive Xbox Live Marketplace Content: A few extra downloadable perks for being a gold member.
Those are the basic differences between Silver and Gold.
Bottom line: to play your Xbox 360 games online, you'll have to purchase a Gold membership.
However, for PC Games it's different.
So basically, if you have an XBox360, you have to have Gold to play correctly.
If you have a PC, you only need Silver because you can play multiplayer with it. You only need to get the gold if you want to play with XBox360 users.