where do i buy roms

[stormrider]

hi
just a few questions if you dont mind

I won an arcade cabinet a while ago and i want to get more games on it
The cabinet was running a ps3 so will it work with a pc? do i just use a hdmi cable to connect the monitor
i want to run a mame on it but i dont know where to get a trust worthy programs/roms. i could google it but you never know what your downloading and its the only pc we have
thanks   I want to buy roms not download from illegal sites
Thanks
adam