What HD video file set to keep/Advise needed

[alegator]

I have the same HD TV video in the following two formats:
Format : AVI
Format/Info : Audio Video Interleave
Format/Family : RIFF
File size : 2.14 GiB
PlayTime : 48mn 12s
Bit rate : 5890 Kbps
Writing application : VirtualDubMod 1.5.10.1 (build 2366/release)
Writing library : VirtualDubMod build 2366/release

Video #0
Codec : DivX 5
Codec/Family : MPEG-4
Codec settings/Packe : Yes
Codec settings/BVOP : Yes
Codec settings/QPel : No
Codec settings/GMC : 0
Codec settings/Matri : Default
PlayTime : 48mn 12s
Bit rate : 5493 Kbps
Width : 1280 pixels
Height : 720 pixels
Aspect ratio : 16/9
Frame rate : 25.000 fps
Resolution : 8 bits
Chroma : 4:2:0
Interlacement : Progressive
Bits/(Pixel*Frame) : 0.238
Writing library : DivX503b1988p

Audio #0
Codec : AC3
PlayTime : 48mn 12s
Bit rate : 384 Kbps
Bit rate mode : CBR
Channel(s) : 6 channels
Sampling rate : 48 KHz
ChannelPositions : Front: L C R, Rear: L R, Subwoofer


and the other video in the follwoing format:
Format : AVI
Format/Info : Audio Video Interleave
Format/Family : RIFF
File size : 2.79 GiB
PlayTime : 59mn 3s
Bit rate : 6758 Kbps

Video #0
Codec : XviD
Codec/Family : MPEG-4
Codec/Info : XviD project
Codec settings/Packe : No
Codec settings/BVOP : No
Codec settings/QPel : No
Codec settings/GMC : 0
Codec settings/Matri : Default
PlayTime : 59mn 3s
Bit rate : 6361 Kbps
Width : 1440 pixels
Height : 1080 pixels
Aspect ratio : 16/9
Frame rate : 25.000 fps
Resolution : 8 bits
Chroma : 4:2:0
Interlacement : Progressive
Bits/(Pixel*Frame) : 0.164
Writing library : Lavc51.9.0

Audio #0
Codec : AC3
Bit rate : 384 Kbps
Bit rate mode : CBR
Channel(s) : 6 channels
Sampling rate : 48 KHz
Resolution : 16 bits
Coherency/PlayTime : 9618500
ChannelPositions : Front: L C R, Rear: L R, Subwoofer


in other words, one is 720p and the other is 1080p. When I watch these videos in my 23" 1600x1200 LCD PC monitor they both have stunning quality and it's hard to say which one is better quality, they look almost the same. My question is, if I watch these videos in a 52" 1080p plasma monitor, will I notice any difference? I don't own such a plasma, but I would like to keep the 1080p video file in case the difference on the plasma is noticeable. If not, I prefer the 720p since it has smaller size (I can store 2 720p videos in a single DVDR5). The total size of the set is approx 25Gb so I can't keep both versions due to my limited hard drive. Thanks for your feedback.

[Krispy Kritter]

There is no good answer. If the source material was HD 1080P, then yes, there should be a noticeable difference on a 1080P capable TV. It would also be helpful to know if your new TV can handle 1080P resolution (1920x1080). Just because a TV accepts 1080P input, doesn't mean it is displaying full resolution. Most LCD and Plasma TV's upconvert/downconvert the video to match their native resolution.

So in your case, I would just keep the 720P vids. The quality will still be good and it will save you space.