Yeah, perhaps I can.
If you read the Technical Handbook under Documentation->Manuals, you will see that the MINIMUM requirement calls for a 1Gig disk.
In my opinion, don't bother to install SME on a disk like that. If you want it to run smoothly as just a firewall, web- and mail-server (no fileservice, mind you), get a disk at least 6,4 Gigs.