@ketanbodas
Why to wait? Nearly all the softwares are Vista ready and every day more and more joing the bandwagon, Drivers are ready. He is ready to spend the money.
There is nothing to stop and wait for. You can nicely upgrade from XP to Vista, the installation shall notify you of all the incompatible softwares with Vista.
Although,to be safe and clea, i would recommend you to first format and install XP again, do not install any other software or update XP or anything, simple clean Vanilla install and then the next thing, get your internet working and start installing vista.
Install all the applications after installing Vista.