Law form?I guess you mean 'firm'.

If you want my  sincere advice,then its its better to apply yourself-you will save a boatload of money.These law firms can be very uncouth.

 If you put a little bit of effort into research its not very difficult.

I did not use a law firm to apply for either my wife's citizenship or my green card,i did it myself and there was absolutely no problem at all.

That's just my opinion.You should go for a law firm if you are more comfortable doing that.About murthy.com,i haven't the foggiest.

If you are working in university and involved in some sort of research, I also suggest you to file yourself under EB2 NIW category. I have seen many Nepalese friends got green card by self filing in EB2. In NIW EB2, lawyers actually ask you to prepare all the documents and completes one form and charge you a handsome money. But you of course should spend some time to prepare the documents.

Murthy law firm seems to be expert in the US immigration. You can guess it from their forum and newsletters too. They claim to sort out several issues that were almost impossible for some other immigration law firm.

You may want to go with them to avoid any problems. I read several law firm doing these filing carelessly and later creating a problem. The only thing about Murthy is they are big, reputed and so expensive.
If it is just little expensive than other law firm, I recommend you go through Murthy. At least, they are sure to avoid any blunders to preserve their reputation. But do post here your experiences if you decide to go for Murthy so that
we all know.

Any idea how much they are taking for EB2/EB3 processing?