Water Heaters - Water Heater Leaking From Drain Valve

I've learned quite a bit searching the forum but really didn't come across my problem.
I've lived in this house for 2 years so I don't know how old the heater is nor could I find anything about it on the internet.
My 40G gas water heater (Sutherland's SN: SLNG 0498 150 444-
Model: CL21V40-5) is leaking out of the drain. It doesn't have a valve with a handle. It has a nipple coming out with a plastic piece with some kind of collar with a nipple attached on it. The collar-type piece looks like it's made to put a wrench on it.
I have a round half quart Tupperware bowl under it to catch the drips and I have to empty it about every 4 hours.
I bought a 3/4" PVC cap and was going to cap it but the threads are messed up so the cap won't go on.
Here are 2 pictures. Sorry they are so huge.

http://i137.photobucket.com/albums/q215/Dawter/100_0037.jpg
http://i137.photobucket.com/albums/q215/Dawter/100_0036.jpg

That water heater was most likely made in April of 1998. The threads on the end of the lousy drain valve are a garden hose thread so a pipe thread cap would not fit. You can buy a brass cap with a garden hose thread in the garden section of the big box mega mart homecenter. Be sure to get a hose washer if the cap doesn't already have the washer.

The normal lifespan of a gas-fired water heater is 8 to 10 years so you are on borrowed time with that one. It may go for another ten years but I suggest that you plan on replacing it in the near future.

you can get the brass cap that furd mentioned or you can get a new drain valve. you need one designed for water heaters or you can just get a regular boiler drain and a 3/4"x3" brass nipple (you will need the nipple with the boiler drain because a male boiler drain wont be long enough)

The threads on the end of the lousy drain valve are a garden hose thread

Oh duh, why was I thinking the end is pipe thread:wall:
I'll get a brass cap tomorrow to see if I can stop the dripping.
I have been searching the internet all over the place and can't find a reasonably priced ($300) 30 gallon gas tank (Energy Efficient) anywhere as I agree with you- I need to look at replacing this one.
Thank you for your wisdom!:)

if you have enough room why not just move up to a 50 gal heater? they are usually not more than $50 more if at all because 50 gal is the most common heater sold. supply and demand. the more made the cheaper to buy

I bought a brass hose threaded cap, put some tape on it and screwed it on. So far...no drips.