Thinking of sellin two cameras and getting a better one

hi all...
i am deliberating whether i shud sell off my two DC's, one's a finepix 2800z and the other a benq dc2300. Not really sure how much each would effect so i could offset my purchase of a new/used camera which is better i.e. ard 3/4 MP, ability to shoot in low-light (pilot light...??so u can see ur subject before the shoot is taken).
All advice are welcomed or queries.