the Cross of St George has indeed been appropriated by racist groups for their own purposes. There is even an organisation of that name which co-ordinates extreme right-wing activity in the UK and has links with neo-Nazis and the ultra-Right in Europe and the US, and was responsible for at least some of the street violence that accompanied the murder of Sarah Payne a few years ago (Sarah Payne was a little girl brutally murdered by a freed paedophile - however in the newspaper and tv inspired public withch hunt that followed, hospital paediatricians and single middle-aged and elderly men found themselves being attacked without provocation by ignorant mobs)
However, this is a modern phenonemon. Before the War, ultra-rightists were often at pains to distinguish themselves from association with St George imagery, and the inspirational myth of St George was called upon frequently during the War against Hitler. St George's Day was until relatively recent times a national holiday and was accompanied with festivals and fairs. It's therefore very sad to see this traditionally English element of our culture, as distinct from British, be thus misused and almost as sad to see it becoming anathema as a result of its misuse.
the Confederate flag is a different matter. it is intimately associated with a political and social culture that enshrined slavery as a central tenet and maintains a revanche influence via symbolism and association to this day that still holds back social and political development in those regions. Now its possible that I'm wrong, and if so I apologise in advance to anyone who I might offend with my next statement, but it seems to me that most of the people who take such pride in being sons or daughters of the Confederacy and display the flag with pride, or in secret, are in sympathy with and wholeheartedly support that history and symbolism and in many ways continue the pro-segregation/anti-integration attitudes that have remained in the South since the Civil War. it's not an innocent symbol that got misused, it is by its very nature loaded with symbolism and a wounded perception of *national* pride.