I have a cisno BM-800, it's a condenser microphone with a 2.5mm output. It's really quite so I have to boost it really high and it ends up being really fuzzy. My friend says I need an external sound card. Should I get a preamp, sound card or what? Any suggestion would help.
If so then you're likely suffering from not enough power. I had the same issues with my ModMic5. The problem is most onboard audio don't put enough power for the mic. Even a lot of 3rd party soundcards, while they have much better output than onboard, still have pretty crappy inputs. The easiest and cheapest way to see if you can boost the power is grabbing an external USB sound card. Something like this will boost your mic so it should be audible and not have to boot the levels so high. For reference, even the people who make my mic were recommending this along side their own USB adapter.
This that adapter works, you know it's a power issue and not a mic issue. From there you can look at more extensive (and expensive) options. I just picked up the Mayflower Arc as it's one of the very few headphone/mic amps on the market. If you do decide to go the route of a 3rd PCIe sound card, make sure to research the mic input.