Arduino sampling accelerometer
You can send transmit roughly 11 bytes per millisecond at 115200 baud. So as long as you restrict your output to 10 characters and a newline per sample, that should be fine. 

The math behind that is 115200 baud means 115200 bit-times/second, and there are 10 bit-times per byte transmitted on the UART (start bit, 8 data bits, and stop bit). So 115200 / 10 = 11520 bytes / second = 11.520 bytes / millisecond (and I round down).

In summary, 100Hz sampling should be easy.

The canonical approach to interval timing is demonstrated in the BlinkWithoutDelay Arduino example. Consolidated it looks like the following:

long previousMillis = 0;
long interval = 10; // interval in milliseconds (10ms =&gt; 100Hz)

void setup() {
   // whatever
   Serial.begin(115200);
   Serial.println("Hello World");
}

void loop(){
   unsigned long currentMillis = millis();
   if(currentMillis - previousMillis &gt; interval) {
      previousMillis = currentMillis;

      // do your task
      Serial.println(analogRead(0));
   }
}