you are right! mine doesn't give equal probabilites. here is a simple python test script:
Code:

---

import random

def rand5():
    return int((random.random() * 5) + 1)

##def rand7():
##    return (rand5()+rand5()+rand5()+rand5()+rand5() - 2) / 3

def rand7():
    answer = 27
    while answer > 26:
        answer = rand5() + rand5() * 5
    return (answer - 5) % 7 + 1

count = {}
for i in range(1000000):
    r = rand7()
    if count.has_key(r):
        count[r] += 1
    else:
        count[r] = 1

print count

---

your version works! but is a version without while or if possible?



<edit>hm... i am not sure but this one seems to work:
Code:

---

def rand7():
    return ((rand5() +
             5*rand5() +
             25*rand5() +
             125*rand5() +
             625*rand5() +
             3125*rand5() +
             15625*rand5() - 19531) % 7) + 1

---

i only found this with some trial and error though! </edit>