Hello,
Normal users should use the current Final version of XnView, which is version 1.70.4. Please see post XnView 1.70.4 for details.
A Release candidate (RC) is a mainly stable version, which is provided to a larger number of people for testing. If the release candidate has few or no serious bugs, it will become the new final release, which will be announced in a new, separate topic in this newsgroup. Typically, the release candidate comes as executable file, only, and has no setup.
If you want to use the latest version and/or have fun testing an application which still might have bugs, the release candidate is the right thing.
At the moment, XnView v1.74 RC1 is available here : http://www.xnview.com/beta/XnView-RC1.zip
If you find bugs, please contact me.
WhatsNew: 
    Added : Gammasat, conbright, autocrop in multi-convert & NConvert
    Added : New submenu for MRUF
    Added : Use EXIF orientation
    Added : EXIF orientation in "JPEG lossless rotation"
    Added : HLS & Sepia in multi-convert & NConvert
    Added : Use of key "context menu" in browser
    Added : Text template (iptc, exif, ...) in multi-convert
    Added : $ for source folder in NConvert
    Added : Fit option for fullscreen
    Added : Scan headers option
    Added : Option to have old zoom feature with left button
    Added : Custom size/ratio
    Added : High quality preview in browser
    Added : Loading WMF in full resolution
    Added : (Advanced) Operations can be moved
    Added : Add/Merge option for batch IPTC
    Added : Flat style thumbnail option (windows only)
    Added : Horizontal/Vertical windows tiling
    Added : FlashCam frame, Cisco IP Phone & JBIG-2 read format
    Added : Lossless crop
    Added : lossless operations in toolbar
    Added : Options for camera RAW format
    Added : Describe on folder
    Added : Use EXIF DPI informations
    Changed : Browser/Show text & Show hexa moved to options
    Changed : jbigkit 1.6
    Changed : MRW,ORF,NEF
    Fixed : Next/Previous
    Fixed : <IPTC:Keywords>
    Fixed : DDS writed by DirectX9
    Fixed : View picture sorted by image property
    Fixed : Move lost item focus
    Fixed : Associations on Xp (windows only)
    Fixed : ESC quit fullscreen view from browser
    Fixed : After "Save As", the picture has now the new name
    Fixed : XWD
    Fixed : When user can write in XnView folder, cache will be created in "Document Settings" (windows only)
    Fixed : 16000x16000 limit for gif files
    Fixed : Resize selection & Fit image
    Fixed : Deselecting item in browser don't update preview (windows only)
    Fixed : Some problems with video player (windows only)
    Fixed : Describe with search results
    Fixed : Multiconvert with CRW/High
    Fixed : -ratio with resize & canvasresize problem in NConvert
    Fixed : XnView Fit & Fit to image
    Fixed : grey scale image resizing
    Fixed : Slow scrolling (windows only)
    Fixed : Playing movie in fullscreen (windows only)
    Fixed : Fit to desktop + fullscreen
    Fixed : Iff writing
    Fixed : Casio makernotes
    Fixed : Problem with old language dll (windows only)
    Fixed : With many files, all thumbnails are not created
    Fixed : Many other things...
Pierre.
			
			
									
						
										
						
