Image..., ...saving quality Options

[Genocide]

i'm making a new layout and i'm wondering if there is a good website you can save bmp files on...and if not...how do people keep their images such high quality even tho if you right click and see the properties...it says it's a jpg file?

jpg files tend to become blurred when you save them on your computer, now i know when you upload a bmp file to a hosting site (such as TinyPic.com) it will give you a jpg file extension (for example: save a pic as "tupac.bmp", upload it and it will give you "tupac.jpg" [even tho tinypic gives you numbers and letters before the extension] but with the same quality as a bmp file)

however, when a bmp file is over a certain size the site will compact the file, in tern making it a smaller picture...how do layout makers (such as dorischu) and (xquizit) make these pictures such good quality AND large size...please help

thankz

EDIT: what would be the correct way to save a jpg file to where it doesn't distort the picture?