Powerline adapters aren't bad. They do tend to get a bad rep though. I know we frequently had them returned at the shop I worked at because people didn't understand how they worked. However, they can work well if you need to extend the network but might have issues with wireless signal strength.
On the same token, Powerline adapters do tend to be slower than most wireless networks. I've not tested any of them recently but I know some original ones were slower than Wireless G. New ones are rated much higher, but as with most any network, your enviroment could play a huge factor in those speeds.
If you already have the wireless router, stick with wifi. In the end, it'll probably be the easiest to implement . Besides, you still will need a router. you'd just be looking at about $30 for a good wireless card vs about $80 for a good powerline set.
