Replace multiple words with the single words in regular replace expression

Hi,, For example we have 5 mp3 files, and we have opened that for editing in mp3 tag ...file name is something like this -

first_simple.mp3
wow_second.mp3
tere_bin.mp3
ya-ali.mp3
shuru ho ja.mp3

actually we want to remove the two words "first" and "ho", with a single word "hello" by the replace with regular expression,,but we want to select both two words at one time,,so plz reply us how can i do this.
I am using v2.69

Why is it so attractive to mess about with amorphous, unstructured strings in filename, when a re-creation of filenames from structured tag fields would be so much easier? What have you got in the tag-fields?

As you want to replace one string constant with another but the scattering of string constants does not follow a pattern you are lost with regular expressions, I guess.
You can employ an action of the type "Format tag-field" for _FILENAME
Format string: $replace(%_filename%,First,Hello,Ho,Hello)

Thanks.....for helping us.....
We wants to ask a thing that in the Format sting - "_ALL" Field is not available,,,can i create that ??