i too use budget ide cables and dont have any problems etc.
as for scarts,hi-fi speaker cables and interconnects they do make a BIG difference if you have a half decent system to start with. throw away the freeby leads supplied and spend say,10-15% of the cost of your system on better cables.
QED 79 strand speaker cable id great for a buget system.costs about 75p per metre.
Ixos scarts are top quality and cost from about £20 upwards.
Cambridge phonos and interconnects are also good and quite inexpensive.
go to a store like richer sounds click here give them a call before you go and say you want to demo some interconnects.most will set up their demo room for you and quite happily let you hear and see the difference between the various cables.you can even bring along your own system and cds dvds that you are familiar with.