In the International Alphabet of Sanskrit Translation (IAST) you can get your answer, where is the problem.
when you'll read the name in any Sanskrit book it is written as " राम" andin the IAST it is written as "rāma", you can see that there is a difference in 2nd character ( ā ) and 4th character ( a ) but most of the time it is not possible to write this with typewriter or in normal fonts in computer also. So people write it as "Rama" only and which is quite obvious. But If you see in this link how it is pronounced or any other site of IAST (Sanskrit alphabet, pronunciation and language) you can make the difference.
It is the same thing what Avinash is trying to say in the last post. When you put an (a) with any consonants it is spoken complete like in the nice example given above "Ma" in "Manoj" where it is really ( a ) but in "Rajesh" there should be ( ā )(as per IAST only). which you can see in any IAST reference. And in that same method it is written as ( rāma = राम ), (arjuna = अर्जुन ) , (kṛṣṇa = कृष्ण), ( Rāmāyaṇa = रामायण) , (Mahābhārata = महाभारत).
But again it is difficult to write ( ā ) all the time so we replace it with ( a ) and than obviously it is difficult to pronunciation it correctly.
But still I think it is just to know this things but not much important to discuss it and criticize each other. Even in the Sanskrit literature also names of Rāma and kṛṣṇa are being written and used in many different ways just to rhyme the words. So i'll say every one above is write in their own way.
