@aroraanant - if allowed to segregate, i would categorise some systems for you:
1. HTiB - these are more than *just* speakers. denon 1312xp (or any newer model, if available) would be my pick. though i don't have a personal experience, but according to widespread feedback, denons are more 'musical' HTiBs as compared to onkyos. moreover, this one has an active sub & also gives you the flexibility to upgrade the system's speakers to something better, if you wish to do so in future. denon HTiBs, in the same category, used to come for quite a higher price earlier (above 40k....still they are a little costlier than onkyos), but to compete with other players in the market, denon reduced the costs, keeping quality almost the same (except that the wooden speakers were replaced with plastic ones). but choice in this segment HIGHLY depends on a personal auditions, as you have already discovered in case of yamaha HTiB earlier. so keep looking & auditioning. you won't need a sound-card in a PC to hook them up with your desktop. these are already equipped with an AVR as you already know. unlike *just* speaker systems, these are capable of HD Audio passthrough, like DTS HD-MA, Dobly TrueHD, etc.
2. Speakers - in this segment, there are quite some good options --> energy take classic 5.1, jamo A102 HCS series & others, pioneer SP-PK21BS (probably the most powerful & bulkier of the lot), and some others which you will get to know when you visit Chittaranjan Park at New Delhi, as told to you by The Incinerator above. with these, you will need either an AVR or a sound-card with a good amp onboard (either of these is a must!).