Greetings.
FRIDAY
Ar: Jum'ah
It is narrated by Abu Huraira and Huraira that the Messenger of Allaah (may peace be upon him) said: It was Friday from which Allaah diverted those who were before us. For the Jews (the day set aside for prayer) was Sabt (Saturday), and for the Christians it was Sunday. And Allaah turned towards us and guided us to Friday (as the day of prayer) for us. In fact, He (Allaah) made Friday, Saturday and Sunday (as days of prayer). In this order would they (Jews and Christians) come after us on the Day of Resurrection. We are the last of (the Ummahs) among the people in this world and the first among the created to be judged on the Day of Resurrection. In one narration it is: "to be judged among them." (Sahih Muslim, Book 4, Number 1862 (
http://www.usc.edu/dept/MSA/fundamentals/hadithsunnah/muslim/004.smt.html#004.1862 ) see also Numbers 1858-1861, 1863)
For more on the ambivalent relationship of Muhammad to Christians, see the article
http://www.answering-islam.de/Main/Shamoun/christians.htm
Speaking of the greatness of the day of Jum'ah (Friday), Muhammad said in a hadith: "On that day [i.e. Jum'ah], Allaah created Adam." Hence Muslims emphasized Friday because Allah created Adam on that day."
Narrated Abu Huraira I heard Allah's Apostle (p.b.u.h) saying, "We (Muslims) are the last (to come) but (will be) the foremost on the Day of Resurrection though the former nations were given the Holy Scriptures before us. And this was their day (Friday) the celebration of which was made compulsory for them but they differed about it. So Allaah gave us the guidance for it (Friday) and all the other people are behind us in this respect: the Jews' (holy day is) tomorrow (i.e. Saturday) and the Christians' (is) the day after tomorrow (i.e. Sunday)." (Sahih Bukhari 2.1, Sahih Bukhari 2.21)
angels record arrival at mosque for Friday prayers, Sahih Bukhari 2.51
first few to arrive for Friday prayers like sacrificing animals,
Narrated Abu Huraira:
The Prophet said, "When it is a Friday, the angels stand at the gate of the mosque and keep on writing the names of the persons coming to the mosque in succession according to their arrivals. The example of the one who enters the mosque in the earliest hour is that of one offering a camel (in sacrifice). The one coming next is like one offering a cow and then a ram and then a chicken and then an egg respectively. When the Imam comes out (for Jumua prayer) they (i.e. angels) fold their papers and listen to the Khutba." (Sahih Bukhari 2.51)
opportune time where Allaah will answer all demand,
Narrated Abu Huraira:
Allaah's Apostle talked about Friday and said, "There is an hour (opportune time) on Friday and if a Muslim gets it while praying and asks something from Allaah, then Allah will definitely meet his demand." And he (the Prophet) pointed out the shortness of that time with his hands. (Sahih Bukhari 2.57)
All these hadiths are an incentive for Muslims to come for congregational prayers on Friday.
Believing that the above traditions are not trustworthy, S.D. Goitein presents an entirely different motivation that may have led to the choice of Friday as the day of Muslim assembly:
http://www.answering-islam.de/Main/Books/MW/friday.htm
Also this is intresting aswel

Prayers (Salat):
The performance of the five daily prayers is required of Muslims. There is no hierarchical authority in Islam, so the prayers are led by a respectable person who knows the Qura'an, chosen by the congregation. These five prayers contain verses from the Qura'an, and are said in Arabic, the language of the Revelation, but personal supplication can be offered in one’s own language. Each Prayer takes on average 5 minutes to perform and involves a series of bowing and prostrations with the mind firmly focused during the entire process. Prayers are said at dawn, noon, mid-afternoon, sunset and nightfall, and thus determine the rhythm of the entire day. Although it is preferable to worship together in congregation at a mosque, Muslims are not restricted in terms of place of prayer as long as a level of security and serenity can be found.
Allaah knows best.
Take care!