The card should fit and work. Be sure you can get win8.1 drivers for it since it appears you machine comes with win8.1
How much it will help depends on your router. If you do not have a dual band router then it will work the same as your current card. If you only have 802.11n on the 5g band on your router it will not use the 802.11ac features it will only run as a 802.11n card.
Something to try before you buy things try to set your router to 20mhz channels. You can then try channels 1,6,11 and see if you get better results...ie you avoid your neighbors better.
When you get the new card you want to do similar on the 5g also. 20mhz channels give you a much better chance of getting one with less interference. 802.11ac uses 80mhz...ie 4 channels so you must get 4 consecutive ones with no interference. There are only 2 blocks of 4 channels total on the 5g range so your odds of getting either of these blocks in a area with lots of neighbors is getting less and less.