hi Rufio! everyone's added their input, so i'll just add in mine as well ^^
you'll need something to hold the water and the fish. ice cream pails would be numerous for your size tank, so try a large sterlite tub or two. the kind people use for storage? you can find them at WalMart or Home Depot or Canadian Tire or whatnot. siphon the water into the tubs, all of the water, well most of it. just leave enough to cover a good portion of gravel, say 3/4 of it. move all the fish into one tub, all the decorations into another. put the filter media in with the fish, and anything else (heater, air stone, airline tubing) in with them. get someone to help you grab the other end of the tank, and haul it carefully into your room and set it down. tug the tubs in, fix up your decorations, refill the water carefully. a nice juice container works well for moving the water, and a bowl above the gravel will displace the water so the gravel isn't messed up. hook up everything that is left (heater, air pump, whatever) and let it all run for fifteen minutes, then add your fish in. i find it's better to do this, because the heater has just started working in the tank and heating it up, but the tub is cooling down rapidly. moving themlater could cause even more stress!
alright, the filter you mentioned, it sounds like an undergravel filter. UGF's are fine for desktop tanks and tanks under 10g, but most others will have a higher bioload that the UGF can't handle. if you can, before redoing anything, take the filter plate out of the gravel and replace is with a powerfilter, like an AquaClear. ask at your local pet store about powerfilters, they'll know what you mean and show you the best bet for your tank. you can still use the airstone, which is the thing that's really filtering your tank now, to produce oxygen for the fish. just bury it under the gravel and hook it to the air pump, and you'll get a nice effect of bubbles heading up from the gravel.
good luck with fishkeeping, Rufio!