I would skip Sony because they're a content provider as well as hardware. Any new, creative, crippling digital rights management methods will probably be imposed on a Sony device before others. This could cause unnecessary headache when trying to play a Blu-Ray through a home theater PC.
If your Blu-Ray drive doesn't come bundled with software for playing Blu-Ray, you'll probably need to plan on buying
Cyberlink PowerDVD pro or ultra. DRM makes playing Blu-Ray movies nearly impossible without ripping to the hard drive and transcoding first, unless you've got player software developed by a company who has surrendered to Sony's DRM and licensing.
I'm inclined to agree with BSA's recommendation on the Wharfedale 2.1 setup over an HTIB. Get something good and build a little as you can, rather than something disposable. You'll be happier with fewer but higher quality speakers than with more but mediocre speakers.
I'm not familiar with retailers in Bangladesh. Are there any online shops where you can find higher end audio gear such as Wharfedale, KEF, Paradigm, German Maestro, Definitive Technology, Klipsch, or similar? Is it less expensive for you to order from India than from the UK?
Are you going to be displaying video through a television or through the PC's monitor? If not, then disregard the rest of this post.
If you are planning to hook your PC up to a television, then continue reading.
Video card: all the major chipset brands have their advantages and disadvantages. But I think if you get an Nvidia GeForce GT610 (like
this fanless Asus card) or better, you'll be pleased. You should also run this
RGB full range toggler utility after driver upgrades to make sure the RGB output isn't limited.
Sound card: doesn't matter. The HDMI out on the video card I recommended above will pass video and multichannel digital audio over a single wire.