Your 800 CFL is fine for veg...maybe as many as 25 young plants.

However, the 500W HPS will only effectively flower about 4 mature plants. Your CFL will be pretty much useless during flower, but they will help with some side lighting and undergrowth foilage retention.

You can squeeze another plant or two IF you have extremely effective reflection going on.

If you went with the Hortilux bulbs for your 500W HID, you could get as many as 6-7 perhaps.

I was a doubter, but those hortilux lamps are the greatest, indeed.