lame question: dl and ul speeds

I have a stupid question: does my upload influence my download speed? I have a 512Kbits cable connection with max upload of 256: if I set my BT client to upload 32KB, will my max dl speed be reduced (to 32KB) or not?

No, because of how TCP/IP works. If you download something, you often have to send packets to the sender that you're ready for more (in other words, upload something). Same applies in the opposite direction.

You can get away with it when using UDP, but most higher protocols don't.