Are you going to be overclocking it at all?
if so, clean the pre-app off with alcohol wipes or similar, and apply the new 'good' stuff you've bought
if not, you can stick with the pre-app stuff, it'll last you fine,
stop yourself from
Mixing the two materials,
one, you'll have far too much tmi on your chip,
two you'll be posting back on here wondering why your new chips temps are so high/You've fried your chip and/or board
Please do not mix them, If you stick with the original pre-app, do that, if you use the new stuff, clean the old stuff off, thoroughly.
Hope this helps