How do I determine the hardware requirements for importing an OSM extract?

I have a 950MB OSM extract I'm trying to import into Postgres using osm2pgsql. All attempts thus far have failed as I've been running out of hard drive space. I have no problem processing metro or individual state extracts. I've encountered nothing but problems trying to import the US Midwest region extract.

I'm likely to build a new VM to process this file so I'd like to get this right. How do I determine the hardware requirements for this process?