i have 500G HDD ...
i installed vista 32 without partitioning, then i shrinked the c drive to 375G...now i have C (375)and D (115G) drives ... that was not satisfying so i decided to use third-party program,,, i managed to make 250G of the C drive unallocated but i encountered booting problems...i tried repairing but no use, so i reinstalled the vista again...everything seems to get back to normal except that i have dual vista systems during booting(i guess both on the same drive), the working, recently installed and the old non-functioning one...

i feel the os has became slower and i want to delete the old one, is that possible and how,,

Thank u in advance