Nick,
A few questions first:
1) Are the Bose speakers the cube-type speakers that are normally connected to a "Bass Module"? If so, they may not work with just any receiver. They are likely low-impedance speakers that will damage most receivers if you connect them. They really are designed to work with the Bass Module (it's technically not a subwoofer), and are mostly useless if you're not using the whole system. Do a search here for "Bose" to see why we really don't like them very much.
2) How will the system be connected to your PC? HDMI? I'm not very well versed on the PC side of things, but if you have a full HDMI (with lossless HD audio) output from your PC, then it may be pretty straightforward to use just about any off-the-shelf HDMI 1.4 reciever.
3) What is your budget? We can't offer much in the way of options without knowing how much you're willing to spend. If the Bose speakers can't be used, and you're faced with getting a whole new system you can expect to pay at a minimum $350-400 for a decent HTiB system that won't have to be scrapped the next time you decide to upgrade.
Finally, how large is the space you're trying to fill with sound? How loud do you like things to be? The 10" Polk subwoofer is not likely to really offer much in terms of decent "home theater" performance. While Polk makes decent speakers, their subwoofers are not much to write home about. You get much better value from a manufacturer who specializes in subwoofers.
Oh, and welcome to the forum!