ENLARGING black and white photos

I have a few scans of B&W photos - 1 BY 1 1/2 , 2 BY 2 1/2 up to 4 X 6
These are old family shots and start really getting grainy when enlarged 50 % or more .

Most of the work is done on a G-4 power mac - so want a program that will run on a power mac . [I will probably upgrade to a mac mini or Imac if canon does not upgrade the lenses I want .] I have a MBP 2.93 - 17 inch but prefer to work with larger screen and keyboard .

Right now I run CS4 and enlarge 10 % save and keep repeating but the grain comes in .

Any ideas about programs or advise ?

I did a search for B%W enlargement - no luck .

Photograph your old pictures with your DSLR.

So far scans are better . Using the 180 macro . I think I might try the 70-200 II with the 2X III . It just takes so long to do the set up and borrow the shots .
Any suggestions on shooting old pictures would help . I come across them every once in a while at parties , weddings etc away from home . Most of time they are hanging on walls - especially in Mexico . Seldom do they even come off walls and almost never out of frame . Pictures can easily be 40 years old with the old wavy glass .
Thanks

Are you only taking one shot of the photos? If so, try photographing them in overlapping segments (top left, top right, bottom left, bottom right) and merge them together in photoshop.

Yes . They are small enough that they will not fill frame . A big picture would be 8 X 10 .
While you could get larger pictures printed , no one did .
One problem is getting level with picture on wall , flare , lighting , reflections from glass .
I have looked / googled but no books jump to front . Most just send you to amazon .

Thanks , I am not converting them . These are old shots , some in frames on walls - either I want them or another family member does .
This has come up a couple of times with shots I / my wife wanted - but I got serious when bother - in law died and 3 people wanted to make colages - The shots were brought to me to enlarge or remove tears , water spots etc .
Right now I am putting all my negatives in binders and sorting . and have found a few of my own when I thought B & W was great .