iam using branded hp system 1 gb ram and 3 giga processor using illustrator and photoshop vga is buitlen is external graphics card nesscessary or not my system performance is not good even i had formated my hard drives due to possibilty of viruses but not yet good plz reply
You will definitely benefit from a dedicated video adapter... especially if you are running Photoshop 11 (CS4). Carefully observe system requirements and check with Photoshop users over at PS forum for recommendations before buying a video card.
You did not supply a lot of system details, but from your information I'd guess that it uses shared memory. In that case, 1GB is marginal (as part of that must be allotted to video memory functions). At the very least, therefore, I'd add memory.