I use OPlayer HD and had no need to convert anything, apart from the odd DVD, search in app store. Good luck
Features:
- Play almost any video formats on your iPad. (WMV/AVI/MKV /RM/RMVB/XVID/mp4/3GP/MPG/)
- Play almost any audio formats on your iPad. (MP3/WMA/RM/AAC)
- Support audio/video streaming over HTTP. (through WIFI or 3G)
- Support USB download files by iTunes.(need update iTunes to V9.1)
- Easily wifi transfer to download media files from your PC to your iPad.
- Support FTP Client to download media files to your iPad.
- Build in web browser to download media files.
- Support ".sub" and ".srt"subtitle.
- Support Mail app attachment open with ... feature.