I've also been looking for a new sound system for my PC and have considered both options you've listed. Despite hating Razer, I looked at the Razer Leviathan due to it's space-saving format. The complaints about the Leviathan dying just outside the one year warranty period (and many instances of rattling after mere weeks or months) convinced me to stay away. Razer's suggestion post warranty was "buy another," and Razer seems to have a generally awful support record. Unless you consider $200 to be chump change, I'd stay away. I also don't know if you're aware, but the soundbar shuts off after 20 minutes of silence when connected to PCs, which many find annoying.
Assuming you buy from authorized resellers, the R1850DB has a 2 year warranty, and the Polk sub has 3 years on the amp/5 years on the woofer. Amazon is an authorized Polk reseller, and Edifier has an online storefront at Amazon, so you're covered there. Both products have solid reviews, so I don't think you can go wrong. My only reason for not pulling the trigger on that combo (yet) is that I'm still trying to figure where I can fit the satellites on my desk.