Stealth, since the plan is to get both HLP and GW into the same server due to financial reasons, it is hard to say what is the optimal hardware. However, I think it is safe to say that even the lowest end dual-core CPU, 1GB RAM and 80GB RAID1 should do fine. As for bandwidth, 1TB per month is pretty safe bet assuming we don't want to move all downloads back to torrents. As for downtime, that greatly depends how much hosting costs.
We now pay $57 per month, that's how much we can afford with ads as long as we would be running Google AdSense. As we aren't now, we can't afford even that, meaning Sandwich has been and still is paying for many months from his own pockets. Anything more than that and we need donations, assuming we will ever be able to run AdSense on hard-light.net again.