Im really woried

I have recently bought a amd +3000, installed it and everything, then i check what its running at at its going at 2.1ghz, isnt it meant to be running at 3ghz??

Nope. I don't know where you saw that, but the AMD 3000+ only runs at 2.1GHz.

Is it like that with all cpu's?

all AMD cpus

Why do people buy them then? if there only 2.1???

Here's two pages worth of opinions regarding the two.
http://www.ozzu.com/hardware/amd-intel-mother-board-t22141.html

AMD are both ahead and behind Intel in terms of technology, and this makes competition in the CPU market really exciting
AMD have been unable (yet) to achieve the clock-speeds that Intel have, but this doesn't matter because AMD chips run more efficiently. As a result they've had to adopt a slightly confusing (at first) naming scheme.

The 3000+ (that you bought) runs at 2.1Ghz, but gives similar performance to Intel chips running at 3Ghz (hence the 3000 name). For this reason, AMD tends to be favoured by modders/overclockers/speed freaks, because running at a lower speed makes it cooler, more overclockable, and require fewer fans. All this means it needs less power = more stability.

I've become a bit of a AMD lover lately (even though this box is a P4). Partly because I agree with their thinking that 64bit is ready for the desktop (Intel have now had to admit that AMD were right the first time, and are fighting for space in the 64bit home-user market).

So in short, don't worry, you made a good choice!

lol, love your post.

Because they have 512MB of L2 cache, which is better than having a slightly faster processor speed and a drastic decrease in L2 cache.

Personally I find it hilarious that people are as concerned as they are with the processor speed, when most people don't purchase ram that matches the clock rate of their new CPU anyway, so they're not taking full advantage of it. What kind of ram do you have? What speed is it? Because unless you have ram that runs at 400MHz (PC3200 and above), you're not getting the most out of your new processor anyway.

You're computer is only as fast as it's slowest component...

being an Athlon xp 3000+ has nothing to do with how fast it runs... it should say on the box somewhere what the actuall speed is...

AMD however, claims that their Athlon xp 3000+ (which runs at 2.1ghz) will out preform a 3.0ghz P4, hence the name... similarly, the Athlon xp 2400+ susposedly outpreforms a 2.4ghz P4...

That is why i believe that the Amd Athlon processors are better than Intel