Updated from 12:46 p.m. EDT

Shares of

Administaff

( ASF) were among the

NYSE's

winners Monday, rising 26.3% after the company posted first-quarter results that topped Wall Street forecasts.

The provider of human resources services posted earnings of $4.6 million, or 18 cents a share, on sales of $299 million. Analysts polled by Thomson First Call were expecting earnings of 12 cents a share on sales of $279.7 million. A year ago the company posted adjusted earnings of 15 cents a share on sales of $252 million. The average number of work-site employees paid per month jumped to 83,729 in the latest quarter, up from 74,792 a year ago. Monthly revenue per employee rose 6% to $1,190, up from $1,123 last year. Looking ahead, Administaff said that it would have 85,750 to 86,250 average worksite employees paid per month during the second quarter, and $202 to $204 in gross profit per work-site employee per month. Shares traded up $3.60 to $17.27.

Tyson Foods

(TSN) - Get Report

rose 3.1% after the company posted second-quarter earnings and sales that beat expectations. The meat company earned $76 million, or 21 cents a share, on sales of $6.36 billion. Analysts were expecting earnings of 17 cents a share on sales of $6.15 billion. A year ago the company earned $119 million, or 33 cents a share, on sales of $6.15 billion. Pretax earnings during the most recent period included $2 million in costs related to poultry and prepared-foods plant closings, the company said. A year ago, costs included $14 million, or 2 cents a share. Looking ahead, Tyson lowered the top end of its 2005 earnings range, saying that it now expects $1.05 to $1.20 a share. Previously, it forecast 2005 earnings of $1.05 to $1.30 a share. Shares traded up 52 cents to $17.41.

Shares of

Sysco

(SYY) - Get Report

rose 2.3% after the food service distributor posted third-quarter results that were better than expected. The company earned $218.2 million, or 34 cents a share, on sales of $7.44 billion. Analysts were expecting earnings of 33 cents a share on sales of $7.39 billion. A year ago the company earned $195.8 million, or 30 cents a share, on sales of $7.03 billion. Sysco said that a reversal of an $11 million accrual for an income tax contingency helped its most recent results. The company said the accrual, based on additional information and supported by a third-party analysis, is no longer warranted. Shares traded up 81 cents to $35.41.

Parker Drilling

(PKD) - Get Report

rose 5.8% after the drilling tools company swung to a first-quarter profit that topped forecasts. The company posted earnings of $3.9 million, or 4 cents a share, on sales of $120.2 million. Results included a charge of a penny a share. Analysts were expecting earnings of 1 cent a share. A year ago the company reported a loss of $4.9 million, or 5 cents a share, on sales of $90.9 million. Shares traded up 31 cents to $5.65.

Shares of

USF

(USFC)

rose 5.9% after

Yellow Roadway

( YELL) sweetened the cash portion of its previously announced bid for USF. Yellow will now offer USF shareholders 65% in cash and 35% in stock. Previously, Yellow offered a 50-50 mix of cash and stock. Under the new terms, USF shareholders will receive $29.25 a share in cash and 0.31584 shares in stock. Shares of USF traded up $2.53 to $45.16, while Yellow Roadway traded up $2.05 to $51.05.

NYSE volume leaders included

Nortel Networks

( NT), down 19 cents to $2.30;

Qwest

(Q)

, up 5 cents to $3.47;

Elan

(ELN)

, up $1.20 to $6.71;

American International Group

(AIG) - Get Report

, up $2.59 to $53.44;

Verizon

(VZ) - Get Report

, down 83 cents to $34.97;

Morgan Stanley

( MWD), down $3.23 to $49.39; and

Lucent Technologies

( LU), up 1 cent to $2.44.

Nasdaq

volume leaders included

Microsoft

(MSFT) - Get Report

, down 7 cents to $25.23;

Sirius Satellite Radio

(SIRI) - Get Report

, up 23 cents to $4.99;

Cisco Systems

(CSCO) - Get Report

, down 1 cent to $17.26;

Intel

(INTC) - Get Report

, up 3 cents to $23.55;

Sun Microsystems

(SUNW) - Get Report

, up 14 cents to $3.76;

MCI

( MCIP), down 83 cents to $25.70;

Oracle

(ORCL) - Get Report

, up 4 cents to $11.60; and

Siebel Systems

( SEBL), down 9 cents to $8.91.