QUOTE (jgalak @ Nov 27 2009, 02:44 PM)

That helps. What about color? Does that determine white/gray/black ice?
The closest equivalent to "color" is the Device Rating of a device. Red is a rating 5-6 Device Rating (although Rating 6 is reserved for Deltaware and Credsticks only, it can be seen as an equivalent to secure commlinks with a System and Firewall rating 6), Orange is a rating 4-5 Device Rating, and Green is a 3 Device Rating. Blue is 1-2, but most things worth hacking would be a Green or higher. You can also just use the color to determine the System and Firewall rating of other systems (by following the above recommendations)
VR 2.0 makes a further distinction of Easy/Average/Hard system ratings. You can just say that Easy has a Firewall of System-2, Average has a Firewall of System-1, and Hard has a Firewall equal to System.
I find that 1st and 2nd edition Shadowrun matrix hosts are more amenable to be converted to 4th edition networks/nexii than 3rd edition writeups. You can preserve the topology there by simply saying that the central CPU node is the main node and that SANs and SPUs are slaved to the CPU. For 1st edition stuff, I'd say that a "Red-3" SPU would be a node that has System 5 and Firewall 3, using the color as the relative system rating and the number as the Firewall rating.
However, I will warn you that early edition Shadowrun adventures were written with the decking portion as a "mini dungeon crawl" for just the decker. This is a major problem in most tabletop games (not so much on Play by Post or other online games, where time is asynchronous), as it means everyone else will be falling asleep while the "decker does his thing". You might want to tone down the detail to keep the game moving and just have a single central node to hack for any given encounter rather than preserving the 1st/2nd edition details.
3rd edition mostly used a security sheaf/tally and the ACIFS structure, which I've found to be very quick to resolve by itself (I think it's better than the crappy 4th edition mechanics, personally, although 4th edition topology and flavor is better). For converting 3rd edition, you'd just use the main System rating as System + Firewall. Easy peasy.