I'm Vietnamese and I can use Chinese, too. Vietnamese structures are absolutely different from Chinese though many sino-Vietnamese words originate from Chinese which are pronounced (sometimes and just sometimes) the same. Vietnamese structures are kind of similar to French while Chinese are to English.

Structure:

Cô gái xinh đẹp đó là bạn của tôi.

= 那个     漂亮的      女人  是   我     朋友。

= That  beautiful    girl   is  my  friend.

Sino -Vietnamese Words:

Gia đình = jia ting

đồng thời = tong shi

*But:

quốc gia =guo jia （ 国家）: nation

nhật kí = ri ji （日记）: diary

hợp pháp = he fa （合法）: legal

Well,why do you have thought that knowing chinese make learning vietnamese easier?It's a GREAT MISTAKE i've seen from learners...Maybe there're several words in Old Vietnamese heard a little bit similar with chinese,but they're completely different and there's not any relation between them:)))

i am vietnamese.. can i help you??..

youre right, some chinese words sounds vietnamese , ex: 政府 (its pinyin is zheng fu), vietnamese will be read: chính phủ....and some chinese grammars rather similar vietnamese, of coz not totally the same but i wil give a simple sentence:  " tôi ăn cơm " (vietnamese) and chinese will be: "我吃饭" , you c ?, their structure is the same, this is just a simple sentence, there are many things to say in grammar,  ;) , enjoy the day~~~~

No, Vietnamese grammar and Chinese grammar are different. Since I'm Vietnamese and I'm learning Chinese (Mandarin). Some words maybe similar. But usually they have different meaning :)