NAS device vs PC as a NAS? Performance

I will backing up non-critical data to these device using Acronis backup software. Basically I just want to shoot system images across the network and have it stored on a NAS. It will be 99% writing to the device..not worried about read. The network is Gigabit.

My question is how does the write performance compare between a NAS specific device (example: Synology DS109 ) and a desktop computer runing Win XP being used as a dedicated NAS solution (example: Dell Optiplex 760, 1GB RAM, nothing running except Win XP minimal services)?

I'm not worried about any other features, users, security, etc...this question is strictly performance related.

thanks for the advice!

Checkout FreeNAS its a much better NAS OS than Windows...

Generally the performance, features and costs of ready-made solutions are inferior to a self-made solution using PC parts. But it does require you to spend more time on it.