To keep the list a little smaller (and track real-world sizes better) I'd suggest 5/10/20/40/80/160/320/500/750MB and 1/2/4GB.
5MB
chdman.exe -createblankhd hdd.hd 153 4 16
10MB
chdman.exe -createblankhd hdd.hd 615 2 16
20MB
chdman.exe -createblankhd hdd.hd 615 4 16
40MB
chdman.exe -createblankhd hdd.hd 615 4 32
80MB
chdman.exe -createblankhd hdd.hd 615 8 32
160MB
chdman.exe -createblankhd hdd.hd 615 16 32
320MB
chdman.exe -createblankhd hdd.hd 1222 16 32
500MB
chdman.exe -createblankhd hdd.hd 1018 24 40
750MB
chdman.exe -createblankhd hdd.hd 1454 16 63
1GB
chdman.exe -createblankhd hdd.hd 524 64 63
2GB
chdman.exe -createblankhd hdd.hd 3876 16 63
4GB
chdman.exe -createblankhd hdd.hd 7752 16 63
all with 512 BPS