Unless you bought your computer for benchmarking (which is fun don't get me wrong), there is no need to be concerned about your benchmarks. Compare your system to Futuremark's similar settings and you should only be concerned if your games run the way you think they should.
its not for benchmarking per-say but it'd def. be nice to get some decent results, its saying i have the worst of 20 similar systems.. makes me wonder with is wrong
The worst of 20 similar systems doesn't mean a lot. They may be similar, but they are not exactly the same, so there may be differences in the build which result in large differences in the score. Though I don't know what the scores were in comparison to yours, there may also not be a big difference in your number 21 score and the number 20 score. So don't worry too much about what is wrong. Everything might be right, for your computer.
The best use that I've found with 3Dmark/Vantage is to compare the results of various changes that I make to my own computer; i.e., did an overclock really help or not, how much did a particular video card help, etc. Another thing it does is to let me know if there is some instability. That is, if the program crashes out, maybe I need to increase the voltage to the ram, CPU, or video card, or maybe I've simply pushed the overclock up a little too high and the computer became unstable.
I have a very similar system to yours. Since it is a BE cpu I prefer to oc with the multiplier over the FSB. Normally I leave it at 18x202-5 for everyday use. I have done a lot of reading about HT and real answers are hard to come by, but what I have found is that that it is recommended to stay as close to spec on the HT for normal use. I know that when these guys really go after extreme OC scores they will push the HT, though after the testing often the equipment is thrown away. I also have 2 4870s in xfire. Your ocing the gpus intrigues me I have never set the mem or freq that high. I do have a AM3 mb and a 955. The best I have done so far is just under 22k (21.7k) in 3Dmark 06. With 2 4890s you’ll do better.
I would be curious as to how high anyone OCs their 4870s and how is that working out for them?