These solutions would work, but there are other options as well. I don't know what VoIP provider you use, but Vonage offers their V-Phone for $40. It plugs into your PC via USB and you plug a headset into the V-Phone and make your calls.

Alternatively, there is the StarCom F1000. That's a WiFi-enabled phone that can connect itself to the wireless network. If your provider has those annoying portal page re-routes to connect (like at most hotels that offer free WiFi), this might not work.

Both of those are Vonage devices, but I'd imagine similar products are available with other providers. They might one or both be compatible with other providers with the right settings.