I was looking at proces and stuff and saw that the 300+ is only 200Mhz slower then the 3400+ which I can probaly over clock, but all I want it for is gaming, it is gonna be coupled with 1024 PC3200 RAM.
I don't think you properly understand what that 200MHz actaually means. It's not the same as 200MHz increase on a Pentium. The performance rating on those processors is a better guide, and the jump from a 3000+ to a 3400+ is more akin to the change from a P4 3GHz to a P4 3.4GHz.
The Athlon64 3000+ will outperform a 3 GHz Pentium 4, and that's plenty enough processing power to drive a decent display card, and thus perfectly adequate for gaming. The display card is the major factor for games - a jump of a few levels of performance rating in the processor doesn't have all that much of an impact. Couple the processor with an NVidia 6800GT or its equivalent, and you'll have a system which will keep you gaming for a long time to come!
there are 2 cores for the amd socket 754's 1 had 1mb of L2 cache and a slower clock speed, one has 512 MB of L2 but 200mhz gain in clock speed, so a 3000+ newcastle core is 2000 MHz my 3400+ newcastle core is 2.4 stock, right now it's 2.69, i doubt you could overclock a 3000+ to that and be stable.