is it possible to convert a vga signal to a dvi signal so that the vga output of a pc can be connected to dvi input of an lcd ??? are there any adapters available???..lamington ppl told me its not possible 
I have DVI->VGA adapter not the other way round..
dont know if it exists..
It may not be possible. If I recall correctly, a DVI port on a gfx card is DVI-I. i.e. it gives a DVI-A(analog) and DVI-D(digital) signal. The DVI to VGA adapter just drops the digital part of signal and gives analog RGB to the CRT monitor.
Now, in the case of VGA port on a gfx card…well it only gives out analog. As the LCD expects a digital signal, it cannot use the VGA port o/p.
Edit: check out the link below for VGA/DVI connectors. You might get some idea.