imac upgrade
I have a imac 20inch early 2009 - is it possible to have a ssd installed in place of the old harddrive?
iMac Line (2012 and Later)
Yes, but considering it's advanced age I would not recommend spending any money on it. However if you decide you want to do it, please use one of the following kits:
https://eshop.macsales.com/shop/ssd/owc/imac/early-2009
Get one of the HD to SSD kits.