ImgBurn should be able to burn those 3 XviD (.avi) files to a dvd-r or dvd+r disc perfectly fine.
and in general if your burning a 16x certified dvd+r (or -R) disc, i would recommend burning it @ 8x for quality reasons as 8x burning on dvd discs is a pretty safe bet for quality.
p.s. for me personally i switch ImgBurn to ‘ISO9660 + Joliet + UDF’ for the file system as when using XBMC (for XBox1 console) to play the XviD video’s it tends to work best this way as with imgburn’s defaults (i.e. ISO9660 + UDF) it cuts off file names to like 8 characters so you cant read the file names of the .avi files properly … so for example if you had a file named ‘The Movie [XviD]’ it would probably be viewed through XBMC as somethng like ‘themovi~’ which would suck and can be hard to read etc
also a word of advice… if you generally have XviD files that are 700MB in size it’s far smarter to burn to DVD disc as it’s cheaper to burn dvd’s than cd’s nowadays… cause look at it this way, you can fit anywhere from 3-6 (6 700MB or 3 1400MB) XviD files to a single dvd disc (which costs .40cents MAX per disc) where as a typical CD costs say about 20cents (maybe a hair less) so to get the same amount of stuff as that single dvd can hold (which only costs 40cents MAX) you would have to burn anywhere from 3-6 CD’s which would cost anywhere between $0.60cents-$1.20… so as you can see unless you have a specif reason to use CD’s over DVD’s then it’s pretty much stupid to burn CD’s for data use nowadays vs dvd’s as DVD are far cheaper to use plus can hold 6-7times as much as a CD can.