It depends on what you are asking for. Do you want the lowest cost desktop that will do email and websurfing fast? Or a good $500 desktop recomendation?
I would go to amazon and best buy and search for all dsktops under $500. The look at the reviews.
You want at leat 4 gig memory, 8 is better.
SSD harddrive at least 250gig. 120 min. Windows will consume about 50 gig once all the updates and add ons roll in. You want plenty of breathing room.
Make sure you current monitor plugd into these units. If its DVI you may need an adapter to plug you monitor in. HDMI and Display port are standard now. Vga....sometimes.
Windows 10.
Video card is on the microprosessor nowadays so that should not be an issue.
Buy with a credit card that doubles the manufactuers warranty.
My go to brands are Dell, Compact/HP, and Asus.