1000 regular-sized tarantulas or one tarantula 1000 times normal size?
For reference, the larger spider would be about as large as a wolf.
Post why you chose what you did.
Edit: My wolf-sized estimate is probably inaccurate. The spider would [i]weigh[/i] as much as a wolf, but I have no clue how large of a spider that would be.
Edit 2:
[spoiler]Spiders and wolves are both primarily made of water, and so will have similar densities. However, spider chitin is only about 2/3 as dense as bone, so the spider will be a bit larger than a wolf. The spider has different proportions, so it would stand wider and closer to the ground than a wolf. Still, all in all the original estimate isn't too far off.[/spoiler]