Yes Avinash,
I agree 273 MB definitely seems like bloated and resource hogger[Bitdefender engine I guess],still what I don't understand is why it so cheap as said by Samuel and considered top in other places?Frankly I don't know which which Anti-Virus to trust,maybe 99.7% A2 Squared Anti-Malware 4.5 is little better[tried its free version was quite good].I sincerely hope Cloud based AV's[like Panda,Rising]is a boon and a blessing though Cloud computing is very much in experimental stage for now so can't say much about it...
PS I have read in other forums and comments that even KIS 2010 has failed to detect some virus,which kind of shook me up a little bit