Intel i7 quad core with hyperthreading...should i use all 8 procesors?

1 core? are the other 7 threads disabled?

it depends on the type of software. if the software is able to use multiple cores, you will see more cores in use. if the software uses only one core, then you'll see only one core in use.
task manager shows all 8 logical cores. you're still using one processor.
you can force the programs to use other cores than the ones they're usually assigned by the os. from task manager, right click on any process in the process tab, select set affinity and you can set that process to run at the manually assigned core.

yea just says 1 core and that i can choose 8.... but what your saying de5_roy is that it automatically will use more cores if it needs too?

no, some software (older software especially) is only designed to use 1 core, and cannot use any more than that, but some is designed to use multiple cores at once

ok.. yea im not using any old software.. but will it make a difference in performance if i set it higher?

no, i would just let it do it's thing

and even today, alot of software is still only uses a single core because it has no need for more processing power

then whats the point to having quad core with hyperthreading?

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if the software is capable of using multiple cores, then yes, it will automatically use more cores.

So you can use programs that can take advantage of four cores and 8 threads.

hyperthreading lets the cpu to split it's core into two logical cores when workload demands it. if the software is optimized for hyperthreading, it can use ht to work better.
a lot of tasks such as video editing, rendering, encrypting benefit a lot from multiple cores and hyperthreading.