Using an 8052 to try to generate video signals (VGA or PAL/NTSC ) without hardware assistance is a hiding to nothing as the processor has to spend so much of its time generating the sync and video signals that its a hard job to get it to do anything else.Video is so sensitive to timing variations in the sync pulse timing that its almost impossible to generate a stable image without jitter.
Personaly i use dedicated hardware to do video stuff either something like the VGA driver VHDL code that you will find in the hardware library or the Dallas Semiconductor arbitary video overlay device which is part number ..erm Ive forgotten but i am sure you can find it.