Molly and Arthur's Age

[Katie]

No: HPFGUIDX 174557

I woke up this morning thinking about HP...and it popped into my head 
that Molly and Arthur must be quite a bit older than Harry's parents, 
Sirius, Snape, and all that group. Because when the books began, Bill 
and Charlie were already into their careers and out of school, so maybe 
20 and 21?

How old do we think the Weasley parents are? Who would have been their 
contemporaries at school? 

Katie