I was wondering what people use for their p2p program. I used to use Limewire but there are to many junk files when searching. So I am now looking for a new one.
You actually should be asking two questions here: which network should I be using, and which client for that network should I use?
As has already been mentioned in this thread, the two networks most worth using are Edonkey/Emule, and BitTorrent.
Now that Edonkey/Overnet is dead, it's really the Emule network, and while there are other clients, most mods and variations have been folded into the freeware Emule client itself. This is a very distributed, robust network that allows you to connect to multiple servers, direct to other clients via Kademelia, and now offers obfusication if you have troublesome ISP. While Emule can reach high speeds, it's not the speed demon that BitTorrent is, but offers a choice of some very rare and eclectic stuff that has otherwise fallen off the rest of the planet. If you can't find anything elsewhere, it will be available on Emule.
BitTorrent is the high-speed, zero-day style network. Clients can talk to each other, but they need trackers, so content can fall off the network in a matter of days, and a tracker going down can trash your download (though this has recently been improved in clients that can remember other clients even if the tracker subsequently disappears). The two best Windows clients are probably UTorrent (very small, fast, straighforward), and the more unusual BitSpirit, (looks prettier, has options up to your ears, and can do all kind of clever things).
Not strictly P2P, but it's also worth looking at binary Usenet newsgroups. If you have access to a good binary news server, or are willing to pay for a subscription, nothing can max out your bandwith (or download caps) like a local binary news server. What started out as text communication has now had binaries shoehorned into it by clunky ascii encoding to Yenc, and content is zapped all over the world to local news servers. No manditory uploads (as with most P2P networks), and mostly local traffic to keep your ISP happy (if they have a binary news server of their own). Content may only be available for a few days before being pushed off the server by new data, or if you subscribe to one of the industrial outfits like Giganews, they currently have something silly, like 90 days retention.
If you're seriously considering the old-style steam-punk of Usenet binaries, you will need a good client to do all the hard work for you, such as Newsleecher, or News Man Pro. I prefer NMP, as it runs with a MySQL backend and can handle anything you throw at it without blinking.