Any problems with these super long kvm cables?

I'm looking to get my computer into the next room from my monitor and so forth. At first I just presumed I wouldnt be able to run a kvm cable that long due mainly to video issues. But then I see that there are KVM cables going as long as 200' at some online shops. I'm really only looking to go from 25'-50' myself... but this just seems odd to me, are there any side effects? I'm looking at one imparticular.. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=64027&item=5770537534&rd=1 , or maybe these.... they say they are thicker and that this is better... http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=42321&item=6762675095&rd=1