i using mio 2wire modem. it is non-wireless. i use a home plug, comtrend 9000. but signal very weak. modem also far fr my PC. like this, should i buy a better home plug, get wireless booster, or get wireless extender?
It's up to you really.
or you can get an N-type based wireless router.
An 802.11N router will have significant improvements in range compared to G based ones on top of a good speed improvment.
Try that first before getting Wireless boosters or extenders, which are essentially the same. They increse the range of the wireless signal.