Hi Whilst all systems I maintain are on DVR's or dedicated servers this little card seems to fit the bill
As for your garden monitoring a cheep alternative I have used is a outside flood light with pir.Just disconnect the light and use the pir to switch an internal light or sounder.(DIY stores sometimes have one with a remote internal buzzer for around £8) Don't do this if you are not competent working on 240v equipment. HTH CJ