Exactly. GOG doesn't support resuming downloads, which is a shame tbqh. I'm sure they're working on a solution though.

Woah, that really sucks. I know that's beta and all that but that's still a problem they must solve ASAP. I'm thinking about buying Fallout Tactics, but knowing that I'd have to download 1.6 GB at once I'll wait until they implement some sort of download management.

This is what I use. It's pretty awesome.
Also, Download StatusBar is handy as well.

"Free Download Manager" is the best for me. You must try it.
www.freedownloadmanager.org

When i first tried to download giants with 'downthemall' it game me a 403 forbidden error. Then i tried d/l the file without it and it worked fine. Was this just coincidence, or does gog not support downthemall? I sometimes have a flaky internet connection too, and have lost large downloads because of this in the past.

I have successfully downloaded Freespace 2 (1.6 Gig) using DownThemAll.
BadAstronaut - Try rebooting your router before you start the download to ensure you don't get hit by a daily disconnect (I think they still do those..)