For starters, if you're trying to stream to your iPad you're using wifi. Wifi isn't the best choice for streaming. Of course, you don't have much of an alternative when thinking about an ipad. If your signal isn't strong with little interference, you will have problems streaming. I don't own an ipad, but if you can increase the buffer size on the video application you are using, you stand a fair chance of never having the buffer go empty and never having it hiccup. Of course, if your signal is just flat out too slow/weak to provide the necessary transfer rates, the only way to fix it is to have the file stored locally on your ipad.
If you have 1 room that you intend to stream ALOT of movies, you could also consider putting a wifi access point in the room connected to your wired LAN.
There is the possibility you have issues with performance because of your server, but since you have no specs at all, I'm going to guess it's wifi. Alot of people have problems with wifi.