The other problem you have is the relatively awful capture capabilities built into gforce/radeon cards etc. The video input side has a really noisy video path, and quite often unbalanced causing dot crawl, ringing, and introducing video noise. They really are only good for tivo like duties, they are just plain awful for video mastering.
Dot crawl shows up much more when viewed on the PC simply because the PC monitor is higher rez and sharper. Some TVs also have digital comb filters to remove some of the dot crawl, so you don't see it as much on the TV, but you do lose some detail.
If you want to get really good results, you should pick up a dedicated capture card like one from Targa (Targa 2000 series for example) which have much cleaner video paths on the input side. They are quite often available cheap 2nd hand. Use a very short and reasonable quality svideo cable.
For optimum results, crack open your laserdisc player and mount some BNC connectors on the back. then run the Y and C outputs to 75ohm BNC connectors with mini coax, and use 75ohm coax cable (times 2) to your capture card (assuming you have one with coax inputs like the targas). This will give you a much better image. Ensure both cables are identical length or you will get chroma shift.
Better still, get a player with RGB out. Some european models had it on the scart output, and many industrial/broadcast models had it. You would not believe how much better the picture looks in RGB, much better colour and almost no crawl at all. Very nice.